Why my hook_block_view doesn't work? I installed "Form block" and it creates blocks. I want change block title via my module, but it doesn't work.

I create module and set function with hook_block_view:

function zzz_block_view($delta = '') {
  $block = array();
  switch ($delta) {
    case 'user_register':
      global $user;
      // Don't display the form to logged in users or if registration is disabled
      if (!$user-&gt;uid &amp;&amp; variable_get('user_register', 1)) {
        $block['content']['form'] = drupal_get_form('user_register_form');
        $block['subject'] = t('MY TITLE IS HERE');
      }
      return $block;
  }
}


What did I do wrong?
hook_block_view() is only invoked for the module that defines the block via hook_block_info().

To alter the content of a block provided by another module, use hook_block_view_alter() instead.