mobile devices not working after 2010 exchange migration

Our Company migrated to exchange 2010. We are having issue connecting mobile devices(samsung, iphones, ect). During exchange active sync set up on the phones the phone will accept the user account info. If we enter in a wrong user name or password we are prompt to enter in correct info so the phone is talking to the server. We get to the end of set up, the last step is usually setting the push times and syc, next we click next or finish and no emails ever get to the phone and the phone will either hand on a loading screen or say try again later.. any thoughts?