Limit access of a SSID to a certain LDAP group

[qrt]

Hello,

Maybe I'm just too stupid to figure this one out, but I have been  
googling around for several days trying to find a solution...

I am running freeradius on Mac OS X Server.
I have a Cisco WLC runnning several APs with multiple SSIDs.

Everything is working fine, except:

I have not found a way to limit access of a certain SSID to a certain  
LDAP group.

I need to have different WLANs for different Users who are in LDAP  
groups.
The user of group A should be able to use WLAN A but not WLAN B and so  
on.

How on earth do I configure this?

Does anybody have any experience with this?

Thanks

Qurt