Menu not displaying child categories of sub categories

[ne0beatsm0rp98]

I have a menu system where customers click on say Computing  then another 4 child categories are displayed, yet i have more child categories within these categories which do not display. You can click on the sub categories so they are set up correctly just they do not show.

As an example my shop link is http://www.computerwormsliverpool.com/shop

Any help would be greatly appreciated.