Use iphone dock with ipad

Error message

• Notice: Undefined index: comment_node_forum_form in drupal_retrieve_form() (line 806 of /var/www/vhosts/theipadguide.com/httpdocs/includes/form.inc).
• Warning: call_user_func_array() expects parameter 1 to be a valid callback, function 'comment_node_forum_form' not found or invalid function name in drupal_retrieve_form() (line 841 of /var/www/vhosts/theipadguide.com/httpdocs/includes/form.inc).