Categories Unrecognised

Hello,

I have an issue with Categories in two areas of my site. The first is on Projects, where I have a main project page displaying projects split into category A and category B. The person who set it up managed to use WPLook-projects to display them as separate. However when I use the same widget and method to show a newly added category C, the display just shows all posts (irregardless of category).

I also have a similar issue on the blog area of my site where posts have been categorised into X, Y and Z. Using several types of ‘Latest news’ widgets to show a list of only X category posts, again just displays all posts. As I say, I’ve tried many different types of widgets so I think the issue must be at the wordpress end to do with how things are categorised?

I think the problems are connected but I cant find where the issue is.