Can't view sub category page

Hey folks,

I have a main category called DESIGNERS
I then have sub categories, which we will called Designer One, Designer Two, Designer Three

If I click DESIGNERS I can see that page fine.
If I click any of the sub categories, I just see the DESIGNERS page again but with the 'correct' url e.g.

http://www.domain.com/DEV/DESIGNERS/
click on a sub category and go to
http://www.domain.com/DEV/DESIGNERS/DESIGNER-ONE/
But it still shows the main DESIGNERS page

If I turn of the SEO URL ReWrites it appears to be ok.

Any thoughts on what I could investigate?

SOLVED:

It turns out I had used an auto generator that had generated duplicate names for the categories and the manufacturer names.

Changing the manufacturer seo urls solved the issue.