Office 365 UM Error

I have migrated a user from an Exchange 2007 server to Office 365 after which my user was unable to acccess their voice mail box. The error message is "Unified Messaging PIN info couldn't be retrieved for mailbox 'kbailey@daxko.com' : There was an error accessing the mailbox using EWS. The requested operation failed with ResponseCode "ErrorUnifiedMessagingRequestFailed". Details : The UnifiedMessaging request failed.. " According to http://msdn.microsoft.com/en-us/library/microsoft.exchange.webservices.data.serviceerror%28v=exchg.80%29.aspx 
 "ErrorUnifiedMessagingRequestFailed" indicates that the user could not be found which makes no sense (Microsoft error messages rarely do) because the user migrated to Office 365 and they are able to do everything else (email, calendar, etc.) When I try to add the dial plan it gives me a HTTP 400 error. Can you guys help me?