Subdomain vBSEO htaccess - Blank Pages

I have two sites using the same domain.

My main site is on http://www.thisis-asite-here.com/forum/

I also have another forum using vBSEO for different content and not relating to the other forum on http://subdomain.thisis-asite-here.com/forum/

I've installed vBSEO but when I upload the .htaccess file, I get a page cannot be viewed message visiting anywhere on the forums. The home page works fine.

What do I need to adjust in the .htaccess file to make it work for my subdomain please?

I think i'd better send a support ticket then ;-)

Replied to your ticket.