Vex motors pulsing under RC

Hello,

I am using a modified version of the Dual Semi program to drive a robot that uses a Vex controller and two 883 IFI PWM controllers to drive a 12v Globe motor robot. the RC works fine on the pwm motors, (I think I am using motor ports 1,2).I just added another VEX motor on channel 5. While it works fine if I say motor[5] = 127;When I try using the RC it pulses like it it is a 1/2 second loop.
Is there something different about how channel 5 and 6 are programmed from the RC unit?

Please help

I didn't find the right solution from the internet.

References:
http://www.robotc.net/forums/viewtopic. … amp;t=2587
Product Video Service

Thanks