After migrating an Exchange Server I noticed that when I added an Distribution Group to my Mail I could not see the members of that group ?
Error when clicking the + sign to open up the members window.
Cannot perform me requested operation. The command selected is not valid for this recipient. The operation failed.
Solution was simple.
Close Outlook first, next go to the folder %APPDATA% –> Local\Microsoft\Outlook
And clear all *.oab Files Open up sync again and everything is working fine again.