Help with forum permission

[pran]

I have a problem with forum permissions. I created a forum accessible only to moderators and admins but moderators are not able to view the forum. The moderators are primary users of a group called "Board Regulars" and additional users of the moderators group. However, if I change their primary membership to "Registered", they can see the forum. The forum has the following permissions:

• (COPPA) Users Awaiting Moderation: Deny all
• Administrators: Allow all
• Banned Users: Deny all
• Board Regulars: Deny all
• Moderators: Allow all
• Probationary Users: Deny all
• Registered: Deny all
• Super Moderators: Allow all
• Unregistered / Not Logged In: Deny all
• Users Awaiting Email Confirmation: Deny all

I tried looking for the code that checks the permission of the user for the particular forum just before displaying it but I couldn't find it. Can someone point me to the right direction? Thanks in advance.