ActiveSync with SSL

This past weekend I enabeled SSL on my Exchange 2003 server running on Server 2003. Now every time one of my users with the Smartphone connects they get the message Synchronization failed. The Security certificated on the server in invalid. contact your system administrator to install a valid certificate on the server and try again. Error Code INTERNET_45.

Does this have something to do with my using my own certificate that I made on the server? Any help would be greatly appreciated.