Teleporting.. Hmm. Make sure that the target map still exists. Otherwise, remake the teleportation command again, just to be sure.

It also might be a case of the map file being there, but the game not having the proper permissions to ACCESS it.. like Adminstrator creating the map, but you're on as Guest, or something. However, that's very unlikely..

I suggest putting in Message events after each line in the event, to make absolutely sure where the error occurs, if it turns out that the map situation is okay.