Valet 561R remote start question

I got this remote start add on piece to work with its own transmitter, but I cannot get it to work with my existing alarm, a Viper 500ESP. Here's the deal:

1)The Valet module's primary harness has a WHITE/ blue 200mA (-) acitvation input.

2) Viper has a channel 3 200mA (-) output, which is also a WHITE/ blue wire. It also has a channel 2 200mA (-) output, which is a RED / white wire.

The problem here is that I am already using the channel 3 output wire to activate a relay to lock my doors (My original lock and unlock output doesn't work anymore). Now, I'm trying to use channel 2 (RED / white wire) from the Viper alarm to activate the remote start, but it doesn't work. Does anyone have any idea why? The manual says that you have to hold the button for channel 2 for 1.5 seconds before it will send a signal (latched output). Can you not do this? Thanks for any help. Oh and the car is a 98 Acura CL.