vex servo module

I've attempted to hook a vex servo module to my arduino with the code provied in the example labled "knob". The actual electric motor just spins and becomes "detached" from the gear. If I rotate the pot(internal to the servo) to the other extreme it works be it keeps turning and the same thing happens.

I opened the servo and measured the Pot. It measured from 2.1k to 114ohms. I looked up the pot(502T) its max is 5k. Is my potentiometer bad causing my servo to keep running to "find" that position either above 2.1k or below 114 ohms? Also, I checked the pot while in the servo circuit.

I also tried to play with my external 10k pot at different extremes. Should I change anything from the example code program because of the vex brand?

Tell us what a vex is, how it is wired, what its spec is (links are good), and what yor sketch looks like.

The is the link the the vex servo module

And this is the example code from the arduino software

// Controlling a servo position using a potentiometer (variable resistor)
// by Michal Rinott

#include <Servo.h>

Servo myservo; // create servo object to control a servo

int potpin = 0; // analog pin used to connect the potentiometer
int val; // variable to read the value from the analog pin

void setup()
myservo.attach(9); // attaches the servo on pin 9 to the servo object

void loop()
val = analogRead(potpin); // reads the value of the potentiometer (value between 0 and 1023)
val = map(val, 0, 1023, 0, 179); // scale it to use it with the servo (value between 0 and 180)
myservo.write(val); // sets the servo position according to the scaled value
delay(15); // waits for the servo to get there

Vex is just a brand name of robotics kit. I bought it a few years ago from radio shack (only because it was local).

Have you read this thread:

...or looked up other information regarding the VEX servos in VEX forums?

Thanks for the reply. I just figured it out. It was a ground issue.