I know this sounds tedious but it must be followed, otherwise, your setup may not work.
IMO, probably the ONLY thing wrong with a Raypak heater is this "secret handshake" to set up the remote!
Turn on heater on, and run both thermostats up to 104.
IMPORTANT, using the mode button, turn the heater to off, THEN remove power from the heater.
Disconnect the 7 pin remote harness from the board. Yep, this too is important!
On the 7 pin remote harness, connect one of the heater control wires (COMM) to the blue wire. Connect the other to EITHER the blk w/org OR org w/blk wire.
Reinstall the 7 pin plug onto the board.
Power up the heater.
Place the heater into Remote mode (press and hold both up and down arrow buttons for 3-5 seconds).
If there is still no function, confirm that the Jandy PDA is displaying the correct water temp. Bad temp sensors will either display an "open" condition, or a temp that is unlikely, like 127 degrees. In which case will never tell the heater to come on.