Per the Victor user manual (
http://content.vexrobotics.com/vexpr..._20130118.pdf), it indicates failed calibration, as others have said.
Start by checking the code and the wiring - are you actually sending one of the joystick axis to the correct port for that victor?
You said you correctly calibrated 3 other victors before hand... can you temporarily swap the PWM cable from one working victor to the bad one and try calibration again (keep the DSC side the same, just unplug from the good victor and plug it into the bad one)?
Have you tried replacing the victor?