help with links in wordpress

I have set up three blogs on my site with links to their category in the sidebar. I used index.php?cat=11 where 11 is the category id number. The problem is that links only work from the homepage. If I go to the blog then try the link in the sidebar to go to another blog, it just reloads the current page. Any idea on how to fix this issue?

Try absolute path like www.yourdomain.com/?cat=11

yep, I did and that worked fine.