Issue with smartdrive turning

We have been having an issuse with smartdrive turn to heading/rotation this is our code. Our robot keeps spinning and never moves past that part of the code

brain Brain;
controller Controller1 = controller(primary);
//left side
  motor L1 = motor(PORT1, ratio6_1, false);
  motor L2 = motor(PORT2, ratio6_1, true);
  motor L3 = motor(PORT5, ratio6_1, false);
  motor_group LeftG = motor_group(L1, L2, L3);
//right side
  motor R1 = motor(PORT10, ratio6_1, true);
  motor R2 = motor(PORT4, ratio6_1, true);
  motor R3 = motor(PORT8, ratio6_1, false);
  motor_group RightG = motor_group(R1, R2, R3);
// drive train control
distanceUnits units = distanceUnits::in;
double wheelTravel = 4 * M_PI;
double trackWidth = 12; 
double wheelBase = 10;
double gearRatio = 2/3;
//drivetrain 
  inertial eyespye = inertial( PORT1);
  smartdrive Deathtrain = smartdrive(LeftG, RightG, eyespye, wheelTravel, gearRatio);
 void autonomous(void) {
   eyespye.calibrate(3);
  LeftG.spin(forward);
  RightG.spin(reverse);
  waitUntil(eyespye.rotation() >= 90);
  LeftG.stop();
  RightG.stop();
  wait(1, seconds);

perhaps use

resetRotation();

or use heading instead of rotation

Thank you We will try that soon Currently, our robot is squeeling in pain.