hey guy any one out their who have done the cms chapter 13 ?

i am getting an error when i try to add a comment
on the article

like....

Notice: Undefined index: article_id in C:\xampp\htdocs\admin\cms_view_article.php on line 11

Notice: Undefined index: article_id in C:\xampp\htdocs\admin\cms_view_article.php on line 12

any suggestion ?

thankz