AJAX回调在自定义Drupal块中没有响应

我在Drupal网站上添加了一个PhantomJS捕获模块。测试功能显示我的配置是有效的，我可以从管理界面使用它。现在，我想把它放在一个网站上，作为自定义块，这样最终用户就可以粘贴一个网站链接并获得它的屏幕截图。

我在模块的末尾实现了这段代码，表单出现在网站上。

/**
* Implements hook_block_info().
*/
function phantomjs_capture_block_info() {
  $blocks = array();
  $blocks['Scraping Block'] = array(
    'info' => t('scraping block'),
  );
  return $blocks;
}
/**
* Implements hook_block_view().
*/
function phantomjs_capture_block_view($delta = '') {
  $block = array();
  switch ($delta) {
    case 'Scraping Block':
      $block['subject'] = 'Scraper';
      $block['content'] = phantomjs_capture_admin_form();
      break;
  }
  return $block;
}

然而，ajax回调不会在提交时启动。我如何测试这个问题？还是我对这个模块的理解有问题？

这是我在phantomjs_capture.module中得到的所有代码，我没有更改任何其他文件。

<?php
/**
 * @file
 * Defines the administration interface and utility functions to use PhantomJS
 * and test screenshot capture functions.
 */

// @todo: hook_help.
/**
 * Implements hook_menu().
 */
function phantomjs_capture_menu() {
  $items = array();
  $items['admin/config/user-interface/phantomjs_capture'] = array(
    'title' => 'PhantomJS Screen capture',
    'description' => 'Screen capture with PhantomJS',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('phantomjs_capture_admin_form'),
    'access arguments' => array('adminster site'),
  );
  return $items;
}
/**
 * The administration form that allows site admins to enter information about
 * the systems installation of PhantomJS.
 *
 * @return array $form
 *  Drupal form array witht the administration form.
 */
function phantomjs_capture_admin_form() {
  $form = array();
  $form['phantomjs_settings'] = array(
    '#type' => 'fieldset',
    '#title' => t('PhantomJS settings'),
    '#collapsible' => FALSE,
  );
  $form['phantomjs_settings']['phantomjs_capture_binary'] = array(
    '#type' => 'textfield',
    '#required' => TRUE,
    '#title' => t('Path to phantomJS'),
    '#description' => t('This module requries that you install PhantomJS on your server and enter the path to the executable. The program is not include in the module due to linces and operation system constrains. See !url for information about download.', array(
      '!url' => l('PhantomJs.org', 'http://phantomjs.org/'),
    )),
    '#default_value' => variable_get('phantomjs_capture_binary', _phantomjs_capture_get_binray()),
  );
  $form['phantomjs_settings']['phantomjs_capture_dest'] = array(
    '#type' => 'textfield',
    '#required' => TRUE,
    '#title' => t('Default destination'),
    '#description' => t('The default destination for screenshots captures with PhantomJS'),
    '#default_value' => variable_get('phantomjs_capture_dest', 'phantomjs'),
  );
  $form['phantomjs_settings']['phantomjs_capture_script'] = array(
    '#type' => 'textfield',
    '#required' => TRUE,
    '#title' => t('PhantomJS capture script'),
    '#description' => t('The script used by PhantomJS to capture the screen. It captures full HD images (1920 x 1080).'),
    '#default_value' => variable_get('phantomjs_capture_script', drupal_get_path('module', 'phantomjs_capture') . '/js/phantomjs_capture.js'),
  );
  $form['phantomjs_capture_test'] = array(
    '#type' => 'fieldset',
    '#title' => t('Phantom JS test'),
    '#description' => t('You can use the form in this section to test your installation of PhantomJS.'),
    '#collapsible' => TRUE,
    '#collapsed' => TRUE,
    '#tree' => TRUE,
  );
  $form['phantomjs_capture_test']['url'] = array(
    '#type' => 'textfield',
    '#title' => t('URL'),
    '#description' => t('Absolute URL to the homepage that should be capture (it has to be a complet URL with http://).'),
    '#default_value' => 'http://www.google.com',
  );
  $form['phantomjs_capture_test']['format'] = array(
    '#type' => 'select',
    '#title' => 'File format',
    '#options' => array(
      '.png' => 'png',
      '.jpg' => 'jpg',
      '.pdf' => 'pdf',
    ),
  );
  $form['phantomjs_capture_test']['result'] = array(
    '#prefix' => '<div id="phantomjs-capture-test-result">',
    '#suffix' => '</div>',
    '#markup' => '',
  );
  $form['phantomjs_capture_test']['button'] = array(
    '#type' => 'button',
    '#value' => t('Capture'),
    "#ajax" => array(
      "callback" => "phantomjs_capture_test_submit",
      "wrapper" => "phantomjs-capture-test-result",
      "method" => 'replace',
      "effect" => "fade"
    )
  );
  return $form;
}
/**
 * Ajax callback for the test PhantomJS form on the administration page.
 *
 * @param type $form
 * @param type $form_state
 * @return type
 */
function phantomjs_capture_test_submit($form, $form_state) {
  // Build urls and destionation.
  $url = $form_state['values']['phantomjs_capture_test']['url'];
  $file = 'test' . $form_state['values']['phantomjs_capture_test']['format'];
  $dest = file_default_scheme() . '://' . variable_get('phantomjs_capture_dest', 'phantomjs');
  // Get the screenshot and create success/error message.
  $output = '<div class="messages status"><ul><li>' . t('File have been generated. You can get it !url', array('!url' => l(t('here'), file_create_url($dest . '/' . $file)))) . '.</ul></li></div>';
  if (!phantomjs_capture_screen($url, $dest, $file)) {
    $output = '<div class="messages error"><ul><li>' . t('The address entered could not be retrieved.') . '</ul></li></div>';
  }
  // Return
  return array(
   'phantomjs_capture_test' => array(
     'result' => array(
       '#prefix' => '<div id="phantomjs-capture-test-result">',
       '#suffix' => '</div>',
       '#markup' => $output,
      ),
    ),
  );
}
/**
 * Validation of the administration form. It tests that the locations given
 * exists and that the PhantomJS binary is executable (by getting its version
 * number).
 *
 * @param type $form
 * @param type $form_state
 */
function phantomjs_capture_admin_form_validate(&$form, &$form_state) {
  // Check that phantomjs exists.
  if (!file_exists($form_state['values']['phantomjs_capture_binary'])) {
    form_set_error('phantomjs_capture_binary', t('PhantomJS was not found at the location given.'));
  }
  else {
    // Only show version message on "Save configuration" submit.
    if ($form_state['clicked_button']['#value'] == t('Save configuration')) {
      drupal_set_message(t('PhantomJS version @version found.', array(
        '@version' => _phantomjs_capture_get_version($form_state['values']['phantomjs_capture_binary']),
      )));
    }
  }
  // Check that destination can be created.
  $dest = file_default_scheme() . '://' . $form_state['values']['phantomjs_capture_dest'];
  if (!file_prepare_directory($dest, FILE_CREATE_DIRECTORY)) {
    form_set_error('phantomjs_capture_dest', t('The path was not writeable or could not be created.'));
  }
  // Check that capture script exists.
  if (!file_exists($form_state['values']['phantomjs_capture_script'])) {
    form_set_error('phantomjs_capture_script', t('PhantomJS script was not found at the location given.'));
  }
  // Remove test form.
  unset($form_state['values']['phantomjs_capture_test']);
}
/**
 * Returns the version number of the currently install PhantomJS.
 *
 * @param string $binary
 *  Optional absolute path with the PhantomJS binary. If not given the default
 *  location is used.
 * @return string|boolean
 *  If PhantomJS is found and executeable the version number is returned else
 *  FALSE is returned.
 */
function _phantomjs_capture_get_version($binary = NULL) {
  // If the binary is not given try the default path.
  if (is_null($binary)) {
    $binary = _phantomjs_capture_get_binray();
    if (!$binary) {
      drupal_set_message(t('PhantomJS binary was not found. Plase intall PhantomJS on the system.'));
      return FALSE;
    }
  }
  // Execute PhantomJS to get its version, if PhantomJS was found.
  $output = array();
  exec($binary . ' -v', $output);
  return $output[0];
}
/**
 * Returns the absolute path with the binray to the installed PhantomJS.
 *
 * @return string|boolean
 *  The executable PhantomJS binary or FALSE if not found.
 */
function _phantomjs_capture_get_binray() {
  $binary = variable_get('phantomjs_capture_binary', '/usr/local/bin/phantomjs');
  if (!file_exists($binary)) {
    return FALSE;
  }
  return $binary;
}
/**
 * Captures a screenshot using PhantomJS by calling the program.
 *
 * @param string $url
 *  The ULR/http(s) to render the screenshot from.
 * @param type $dest
 *  The destionation for the rendered file (e.g. public://fecthed_images).
 * @param type $filename
 *  The filename to store the file as in the destination.
 * @param type $element
 *  The id of the DOM element to render in the document.
 * @return boolean
 *  Returns TRUE if the screenshot was taken else FALSE on error.
 */
function phantomjs_capture_screen($url, $dest, $filename, $element = NULL) {
  // Get PhantomJS binary.
  $binary = _phantomjs_capture_get_binray();
  if (!$binary) {
    drupal_set_message(t('PhantomJS binary was not found. Plase intall PhantomJS on the system.'));
    return FALSE;
  }
  // Check that destination is writeable.
  if (!file_prepare_directory($dest, FILE_CREATE_DIRECTORY)) {
    drupal_set_message(t('The PhantomJS destination path (@dest) was not writeable or could not be created.', array(
      '@dest' => $dest,
    )));
    return FALSE;
  }
  // Get absolute path to PhantomJS script and the destionation file.
  $script = realpath(variable_get('phantomjs_capture_script', drupal_get_path('module', 'phantomjs_capture') . '/js/phantomjs_capture.js'));
  $dest = drupal_realpath($dest . '/' . $filename);
  // Run PhantomJS to create the screen shot.
  $output = array();
  if ($element) {
    exec($binary . ' ' . $script . ' ' . $url . ' ' . $dest . ' ' . escapeshellarg($element), $output);
  } else {
    exec($binary . ' ' . $script . ' ' . $url . ' ' . $dest, $output);
  }
  // Check that PhantomJS was able to load the page.
  if ($output[0] == '500') {
    return FALSE;
  }
  return TRUE;
}
/**
* Implements hook_block_info().
*/
function phantomjs_capture_block_info() {
  $blocks = array();
  $blocks['Scraping Block'] = array(
    'info' => t('scraping block'),
  );
  return $blocks;
}
/**
* Implements hook_block_view().
*/
function phantomjs_capture_block_view($delta = '') {
  $block = array();
  switch ($delta) {
    case 'Scraping Block':
      $block['subject'] = 'Scraper';
      $block['content'] = phantomjs_capture_admin_form();
      break;
  }
  return $block;
}