Menu URL Problem

I have created a URL as follows,

$items['supporters/%arg'] = array( 'title' => t('Support'),
'page callback' => 'drupal_get_form',
'access arguments' => $access,
'page arguments' => array('support_mainonepids',1),
'type' => MENU_CALLBACK,
);

But when i run this as "?q=supporters/131317", i am getting page not found error.

What might be the problem? Can anyone please help me here?