Tray PID Not Working

Programming Support VEXcode Pro V5 Text Tech Support
1

So I have been trying to create a PID for the tray on our robot but for some reason, the code does not work… I was wondering if anyone would be able to tell me why when I press the tray buttons, the tray only moves backwards and continues to move backwards even when I let go of the buttons. Any help would be appreciated!

Code:

/*---------------------------------------------------------------------------*/
#include "robot-config.h"
vex::competition    Competition;
/*-------------------------------Variables-----------------------------------*/
double ColumnTarget = 200;
double ColumnDesired;
double ColumnKP = 0.0;
double ColumnPreviousError = 0.0;
double ColumnDerivative = 0.0;
double ColumnKD = 0.0;
double ColumnIntegral = 0.0;
double ColumnKI = 0.0;
double ColumnError;
`/*---------------------------------------------------------------------------*/`
/*                          Pre-Autonomous Functions                         */
/*---------------------------------------------------------------------------*/
void pre_auton( void ) {
}
/*---------------------------------------------------------------------------*/
/*                              Autonomous Task                              */
/*---------------------------------------------------------------------------*/
void autonomous( void ) { 
}
/*----------------------------------------------------------------------------*/
/*                              User Control Task                             */
/*----------------------------------------------------------------------------*/
void usercontrol( void ) {
  while (1){
    if(Controller1.ButtonB.pressing()) {
        ColumnDesired = 20;
        ColumnKP = 0.02;
        ColumnKD = 0;
        ColumnKI = 0.0;
    }
    else if(Controller1.ButtonA.pressing()) {
        ColumnDesired = 0;
        ColumnKP = 0.02;
        ColumnKD = 0;
        ColumnKI = 0;
    }
    ColumnError = pow((TrayTilter.rotation(rotationUnits::deg) - ColumnDesired),3);
    ColumnDerivative = ColumnError - ColumnPreviousError;
    if (((TrayTilter.rotation(rotationUnits::deg) - ColumnDesired) < 5.0) && ((TrayTilter.rotation(rotationUnits::deg) - ColumnDesired) > -5.0)){
        ColumnIntegral = 0;
    }
    else {
        ColumnIntegral += ColumnError;
    TrayTilter.spin(fwd, (ColumnError * ColumnKP + ColumnDerivative * ColumnKD + ColumnIntegral * ColumnKI), voltageUnits::volt);
    }
    ColumnPreviousError = ColumnError;
    vex::task::sleep(20);
  }
}
int main() {
    pre_auton();
    Competition.autonomous( autonomous );
    Competition.drivercontrol( usercontrol );
    while(1) {
      vex::task::sleep(20);
    }
}