Article ID: 959388 - View products that this article applies to.
When you try to expand a group in Microsoft Office Communicator, you may receive the following error message:
The following error may also be logged in the IIS W3SVC log on the Office Communications Server 2007 server:
Cannot perform this action, and the cause is unknown. Contact your system administrator to investigate this problem.
The LDAP query in the Active Directory NTDSA Diagnostics Logging may also include objectCategory=CN=Person inside the query processor.
2008-08-08 08:08:08 W3SVC1 127.0.0.1 POST /GroupExpansion/Int/Service.asmx/ExpandDistributionList - 443 127.0.0.1 Mozilla/4.0+(compatible;+MSIE+7.0;+Windows+NT+5.2;+.NET+CLR+1.1.4322;+.NET+CLR+2.0.5 0727) 500 0 0
This problem occurs because the Office Communications Server 2007 Web Components Distribution List Expansion Service found two or more entries in Active Directory that were a Group, a User, or a Contact (possible group for trusted forest). This occurs when at least two of these objects shared the same mail (SMTP) attribute. This is an unexpected configuration.
A secondary problem is that the LDAP query that is being used inside the Web Components Distribution List Expansion Service incorrectly searched with a filter of objectCategory is "CN=Person." This applies to both contacts and users.
To work around this issue, make sure that all users, groups, and contacts do not share an SMTP address.
To resolve this issue, apply the hotfix that is described in Microsoft Knowledge Base article 959385.
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
959385The hotfix now uses a compound query that will search only groups and contacts (possible groups from another forest).
(http://support.microsoft.com/kb/959385/ )Description of the update package for Office Communications Server 2007 - Web Components November 2008
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
To confirm that two objects are sharing the same mail attribute value, an administrator can run one of the following tests.
How to test with Windows Address Book - Windows People Search (easy)
How to test with Ldp.exe (advanced)