Consider the following scenario:
You deploy a Group Chat server in a Microsoft Lync Server 2010 environment.
You add a user to a Distribution Group (DG), and the DG is a member of a Group Chat room in the environment.
The user tries to join the Group Chat room.
In this scenario, the user cannot join the Group Chat room.
This issue occurs because the Group Chat server encounters an exception when it tries to synchronize with Active Directory Domain Services (AD DS).
To resolve this issue, install the following cumulative update:
2803651 Description of the cumulative update for Lync Server 2010, Group Chat: March 2013
For more information about a similar issue, click the following article number to view the article in the Microsoft Knowledge Base:
2783949 User in a DG does not receive a chat room invitation when the user signs in to an Office Communications Server 2007 R2, Group Chat client For more information about how to deploy Group Chat Server, go to the following Microsoft website: