I'm getting daily questions on my post about how to secure your SQL CE Merge Replication application, and most of them revolve around the dreaded 28037 SQL CE replication error (which means that the PDA cannot connect to the SQL CE IIS virtual directory).
I'm posting a link to a good Microsoft KB article that shows you how to troubleshoot the SQL CE replication error codes and what they actually mean. Feel free to post a question to my earlier thread, but you might want to check this KB article out first. It'll probably save you some time.
Read: Microsoft SQL Server 2000 Windows CE Edition Connectivity Issues