Affiliate Links redirecting back to root domain

I am setting up a few affiliate links and while testing them out, I am getting a weird redirect. Here is my situation:
If I go to http://backstage.roosteromg.com, it works fine, but if I go to http://backstage.roosteromg.com/aff.php?aff=012, it redirects back to http://roosteromg.com.

Everything else seems to work fine, only the affiliate links.

Any ideas? Thank you.