How RTC Authorization is done?

Hi

We are using RTC 3.0.1 with WAS7 and LDAP/Active Directory.

Can someone explain what's the authorization procedure after I key in id/password? I thought was something like this:
1. From my login id, using "Base User CN" to locate this user in LDAP.
2. Once find, get a list of Jazz groups from its memberOf.
3. Confirm the group existing using "Base Group CN" to locate these groups in LDAP?

For IBMers, I have a PMR 56693,999,649 opened, but I am having a hard time to communicate with your support engineer.

I got this error during a login.
https://jazz.net/forums/viewtopic.php?t=20008&highlight=jirong

Thanks
Jirong