1. The database must compile without error.
2. The database format must be equal to the Access version. That means that A2003 can only make an .mde file out of your .mdb if the .mdb is in A2003 format. A2003 and A2002 cannot make .mde out of databases stored in earlier versions of Access. If you need to make an A2K .mde, you need to make it from an A2K version of Access. If you need to make an AXP .mde, you need to make it from an AXP version of Access, etc.