Specifying a name to the destination and teleport triggers would help depending on what teleporter you're using. You simply have to add destination when adding a new field. The value is the teleport name and the name is the type of the trigger, you want to use destination as the name of the target while using a teleport trigger. Also, it be easier if you use some teleporter objects to help you with an inactive and an active teleporter and have them placed on the level so the marble knows when the teleporter is active or not. It's best if you use switch balls, teleporter (known as repair bay as the texture's name), warp light or some other that can remind the marble where it's going to. You don't have to have teleporter objects in the level if you wish.