Vex Light Sensor on FRC Bot

[Aerex]

We tried to use a vex sensor onto our FRC robot to be used to count revolutions by counting a series of alternating black and white tape on a motor. However there is something wrong with my code.

#include "Main.h"

void Autonomous ( void )
{
      int c = 1; 
      unsigned char light; 
      int a = 0; 
      int b = 0; 
      int value = 0; 

      while ( value <= 5 ) //the transition of White to Black five times
      {
            SetPWM ( 10 , 190 ) ; //
            SetPWM ( 11 , 190 ) ;
            light = GetAnalogInput ( 1 ) ;
            if ( light >= 0 && light <= 99 ) //interval of white (Bright)
            {
                  a = 1 ;
                  PrintToScreen ( "a: %d\n" , (int)a ) ;
                  PrintToScreen ( "Light: %d\n" , (int)light ) ;
            }
            if ( light > 99 ) //interval of black (Dark)
            {
                  b = 1 ;
            }
            if ( a == 1 && b == 1 )
            {
                  value++ ; //problem starts here
                  a =0 ;
                  b = 0 ;
            }
      }
      SetPWM ( 10 , 127 ) ;
      SetPWM ( 11 , 127 ) ;
}

At the incremental of the variable value the RC begins to count continously up to five at the first instance and then it stops. I want it to only increment the variable value one at a time so that I can see a smooth transition. I started to believe that the vex light sensor is not capable to be used for FRC. Anyone know the problem or should I just use at gear tooth sensor. I appreciate the response.