Can't login to mailbox when database is on some DAG members

Hello all,

I have a new DAG we setup with 4 server 2 in each site. Exchange 2013 on Serve 2008 R2.  When the database is activated on any server in site A, everything works perfect.  When the database is moved to site b, users sometimes have issues logging in to OWA and Outlook.  Both site have DC's in them.

Any ideas what could be wrong or where to start looking?

Thanks in advance for any help.