How do i Add table button (tried everything with no joy!)

Hi,

I'm using a CMS system and in this system they use CKeditor. I have used Ckeditor before and had no issues adding removing buttons but for some reason It won't let me add the Table button in to the Ckeditor. No matter what I do it just doesn't display

Can some help please?

Im using PHP if thats any help

Many thanks
Joe