Problem using two transmitters

[jamesgecko]

My team finally finished building our robot modules and combined them together into a complete robot.

The way our 'bot is built demands that we use two transmitters.

Transmitter 1 should command motor ports 2, 3, 7 and 8.
Transmitter 2 should command all the other motor ports.

The trouble is, when we turn on the transmitters, #1 does everything and #2 does nothing.

We have a jumper on controller port 15 to use tank controls.

We've hacked a fix using SET PT (and turning down all motor ports not used by that transmitter), but that seems like a clumsy way to do it.

Has anyone else had problems/solutions with this?