Two usersgroups on a user - one forum showing up?

[HCF.net]

Hi there, say for example I have:

a user with their primary usergroup as 'Events Team' and with a secondary user group as 'Development Team' - each of the users are supposed to see both the Events Team forum and the Development team forum I have created... so they can only see one forum, their primary usergroups forum (Events Team)

Why is this and how can I fix it without using access masks?

[glennybee]

Check the forum permissions. Check that the Development Team usergroup has permission to see the forum.

[Marco van Herwaarden]

Make sure the Primary usergroup has "Allow Users to have Member Groups" set to Yes.