In Zend Framework Zend_Db_Table::getDefaultAdapter

after serching up and down the internets, finding no proper answer, I am asking you:

I want to implement a getAuthAdapter(array $form)

private function getAuthAdapter(array $form) {  

  $authAdapter = new Zend_Auth_Adapter_DbTable(
     Zend_Db_Table::getDefaultAdapter(),
     'user',
     'email',
     'password',
     'MD5(?) AND hidden = "FALSE"');   
  $authAdapter->setIdentity($form['email'])
     ->setCredential($form['password']);

  return $authAdapter;
}

To establish a database connection, I added following lines to my application.ini

    resources.db.adapter = "PDO_MYSQL"
    resources.db.params.host = "localhost"
    resources.db.params.username = web5
    resources.db.params.password = ACv8vSdn
    resources.db.params.dbname = usr_web5_1
    resourses.db.isDefaultTableAdapter = true

But after trying the script I experience following error:

Application error
Exception information:

Message: No database adapter present
Stack trace:

0 /usr/share/php/libzend-framework-php/Zend/Auth/Adapter/DbTable.php(140):     Zend_Auth_Adapter_DbTable->_setDbAdapter(NULL)
1 /var/www/web5/html/application/controllers/LoginController.php(49): Zend_Auth_Adapter_DbTable->__construct(NULL, 'user', 'email', 'password', 'MD5(?) AND hidd...')
2 /var/www/web5/html/application/controllers/LoginController.php(23): LoginController->getAuthAdapter(Array)
3 /usr/share/php/libzend-framework-php/Zend/Controller/Action.php(513): LoginController->indexAction()
4 /usr/share/php/libzend-framework-php/Zend/Controller/Dispatcher/Standard.php(295): Zend_Controller_Action->dispatch('indexAction')
5 /usr/share/php/libzend-framework-php/Zend/Controller/Front.php(954): Zend_Controller_Dispatcher_Standard->dispatch(Object(Zend_Controller_Request_Http), Object(Zend_Controller_Response_Http))
6 /usr/share/php/libzend-framework-php/Zend/Application/Bootstrap/Bootstrap.php(97): Zend_Controller_Front->dispatch()
7 /usr/share/php/libzend-framework-php/Zend/Application.php(366): Zend_Application_Bootstrap_Bootstrap->run()
8 /var/www/web5/html/public/index.php(26): Zend_Application->run()
9 {main}  

Request Parameters:

array (
  'controller' => 'login',
  'action' => 'index',
  'module' => 'default',
  'email' => 'test@domain.com',
  'password' => 'test',
  'login' => 'Login',
)

You might want to check you bootstrapper and debug your code which loads the db.