Wireless updates enterend in to our blackberry units are no longer wirelessly updating on the exchange server/Calendar. However when we make a change on the exchange side it does synch up with the handheld units.
Can someone please offer suggestions on how we can resolve this issue.

have installed a new Exchange Patch on your Exchange Server?

Calendar issues are usually becoz of improper rights (make sure the service account has send as, receive as, administer information store, view only administrator). Or the version of CDO.dll does not match on the BES and the Exchange. If you have a clustered environment, make sure the rights have been replicated accross all servers.

I will take a look right now...We did recently upgrade our exchange server.
Unfortunately the Network Admin/Engineer left recently...So we're scrambling to fix multiple issues...Thx