Can't assign a category to a 'Portfolio' post

Hi all,

I hope someone can help. I can’t seem to assign a category type to a portfolio post. The tab on the right hand side that normally appears when editing a new post is not there.

If I go to create a new post, the tab is there and I can give it a category, when I flick back to the portfolio post, it is no longer there.

Can anyone help?

Many thanks,

Zak