"；致命错误:找不到类“；zend框架1

我在一个名为signin-zend framework version 1的模块中创建了一个名称为signin的表单，上面写着"找不到类'sign_form_signin'"

这是表单代码：

    <?php
class Sign_Form_Signin extends Zend_Form
{
    public function init()
    {
        $this->setAction("/sign/in");
        $this->setMethod("post");
        $username=new Zend_Form_Element_Text("password");
        $username->addValidator(new Zend_Validate_Alnum())
                ->setRequired(TRUE)
                ->setLabel("نام کاربری: ")
                ->setAttrib("size", "25");
        $password=new Zend_Form_Element_Password("password");
        $password->addValidator(new Zend_Validate_Alnum)
                ->setRequired(TRUE);
        $submit=new Zend_Form_Element_Submit("submit");
        $submit->setLabel("ورود");
        $this->addElement($username);
        $this->addElement($password);
    }

}

这是Application.ini

[production]
phpSettings.display_startup_errors = 0
phpSettings.display_errors = 0
includePaths.library = APPLICATION_PATH "/../library"
bootstrap.path = APPLICATION_PATH "/Bootstrap.php"
bootstrap.class = "Bootstrap"
appnamespace = "Application"
resources.frontController.controllerDirectory = APPLICATION_PATH "/controllers"
resources.frontController.params.displayExceptions = 0
resources.layout.layoutPath = APPLICATION_PATH "/layouts/scripts/"
resources.view[] =

resources.db.adapter = "PDO_MYSQL"
resources.db.params.dbname = "test"
resources.db.params.host = "localhost"
resources.db.params.port="8889"
resources.db.params.username = "root"
resources.db.params.password = "root"
resources.db.params.charset  = "UTF8"
resources.frontController.moduleDirectory = APPLICATION_PATH "/modules"
[staging : production]
[testing : production]
phpSettings.display_startup_errors = 1
phpSettings.display_errors = 1
[development : production]
phpSettings.display_startup_errors = 1
phpSettings.display_errors = 1
resources.frontController.params.displayExceptions = 1

这是控制器代码：

<?php
class Sign_IndexController extends Zend_Controller_Action
{
    public function init()
    {
        /* Initialize action controller here */
    }
    public function indexAction()
    {
        // action body
    }
    public function inAction()
    {
        $form=new Sign_Form_Signin();
        $this->view->form= $form;
    }
    public function outAction()
    {
        // action body
    }

}

你知道问题出在哪里吗？