Here is my sample program for syncing two motors together.
Also, RobotC 1.07 is available to download from the forum. It has some bug fixes and a few added functions.
Good Luck B-)
nSyncedMotors = synchAB; // Motor ‘B’ is slaved to motor ‘A’
nSyncedTurnRatio = 100; // Move in a straight line
nMotorEncoder[motorA] = 0;
motor[motorA] = 100;
nxtDisplayTextLine(2,"Enc A=%d", nMotorEncoder[motorA]);
nxtDisplayTextLine(3,"Enc B=%d", nMotorEncoder[motorB]);