[Typo3] CHC-FORUM fe-users - forumgroup problem

[dieter]

I have a CHC Forum and a sysfolder called podiumusers.
I have a website usergroup "podiumusersgroup", to which the frontendusers belong,  and a forumgroup "podiumforumgroup" 
to which the website usergroup belongs.

Now in my conferences I grant READ access to anonymous, and READ and WRITE acces to my forumgroup.
The same forumgroup I give permission to include attachments.
In my categories I leave everything blank.

BUT: when I log in, I can see that I m logged in, but I can't post any messages and it says:
"You must login to post a message to this conference."

Seems as if the forum doesn't make the connection between the usergroup and the forumgroup?!
Where do I go wrong????

thnx