Hook not returning any form

Hi,

Please look at following code:

function mymodule_menu() {
    $items = array();
    $items['user/register/%'] = array
    ( 
        'page callback' => 'drupal_get_form',  
        'page arguments' => array('mymodule_user_register'),
        'access arguments' => array('access content'),
        'type' => MENU_CALLBACK,
    );  
      
    return $items;
} 

function mymodule_user_register(&$form_state, $doctor) {
   $form['email'] = array(
    '#type' => 'textfield',
    '#title' => '',
    '#size' => '20',
  );
  $form['submit'] = array(
    '#type' => 'submit',
    '#value' => 'Subscribe',
  );
  return $form;
}

The issue is that this hook is not returning any form.

Please tell me what i am doing wrong here.

Regards,
Kuldeep.