Win2003 server Upgrading Problem

[rvrajeev]

We have windows 2003 servers which we are trying to upgrade to windows 2003 R2 . During the Adprep I am getting following error and would appriciates if some one could guide me how to go forward with this error.

125: CN=Device,CN=Schema,CN=Configuration,DC=Cracknell,DC=com
Entry DN: CN=Device,CN=Schema,CN=Configuration,DC=Cracknell,DC=com
Add error on line 2086: Unwilling To Perform

The server side error is "Schema update failed: attribute in may-contain does not exist."

124 entries modified successfully.

An error has occurred in the program

thanks

Rajeev