我需要将联系表单数据存储到数据库中，我做了一些代码，但在 IndexController.php 中出错

错误：

  Fatal error: Call to a member function setGuestName() on a non-object in IndexController.php
  {main}( ) - index.php
  Mage::run( ) - index.php(line:87)
  Mage_Core_Model_App->run( ) - Mage.php(line:684)
  Mage_Core_Controller_Varien_Front->dispatch( ) - App.php(line:354)
  Mage_Core_Controller_Varien_Router_Standard->match( ) - Front.php(line:172)
  Mage_Core_Controller_Varien_Action->dispatch( ) - Standard.php(line:250)
  Test_Contacts_IndexController->postAction( ) - Action.php(line:418)

我的代码：

  $model = Mage::getModel('contacts/contacts');
  $model->setGuestName( trim($post['name']) );
  $model->setGuestEmail(trim($post['email']));
  $model->setGuestTelephone(trim($post['telephone']));
  $model->setGuestComments(trim($post['comment']));
  $model->setGuestAttachment(trim($post['attachment']));
  $model->save( );