This one keeps getting me and I thought if I wrote it down maybe .. just maybe next time I would remember.
In your current session if you are searching for an Object .. A users mailbox in my case, and you are only getting results from one of the exchange servers run the following:
Set-AdServerSettings -ViewEntireForest $true
This will set your commands to search all of the exchange servers. Just so you don’t have to mess with the -server variables.