Seeedstudio Motor Shield V2 problem running 2 DC motors

Hello! I am trying to control 2 separate DC motors via the Seeedstudio Motor Shield V2 and 2 potentiometers (one to control each motor) connected to open analog ports on my UNO. Getting some odd behavior from the motors, though.

What I want: I want to be able to adjust the speed of the motor on channel 0 by twisting pot. A, and simultaneously adjust the speed of the motor on channel 1 by twisting pot. B.

What I'm getting: When I twist pot. A on, motor on channel 0 sits motionless and makes an odd clicking sound. Pot. B does nothing alone, but when I turn both potentiometers up, motor on channel 0 starts moving EXTREMELY fast, while the motor on channel 1 does not move.

The code I'm trying to use:

#include "MotorDriver.h"
MotorDriver motor;

int velocityA;
int velocityB;

void setup() {

  motor.begin();
}

void loop() {
  // Read values from my 2 potentiometers
  // connected to Analog 0 and Analog 3
  int potValA = analogRead(A0);
  int potValB = analogRead(A3);

  // Convert the input range of the potentiometers
  // to the output range of the Motor Shield V2
  velocityA = map(potValA, 0, 1023, 0, 100);
  velocityB = map(potValB, 0, 1023, 0, 100);

  // Run the motor on channel 0 and the motor
  // on channel 1 at their respective speeds
  motor.speed(0, velocityA);
  motor.speed(1, velocityB);

  delay(2);
}

I've also tried the above code with a serial monitor, and the potVal and velocity values appeared to be correct.
I am not sure what I'm doing wrong, as I've looked the seeedstudio wiki page up and down, and found nothing.

I would greatly appreciate it if someone could help and/or provide a solution! Thank you!

---Wolfram1914

You need to go fault-finding.

Test each motor channel separately with some known speed values and check they work,
swap the motors over to ensure both motors are working the same.

Check your power supply is adequate for the load, check your motor controller is adequate
for the motors. Perhaps you should have said what motors you are using, after all they
might be entire inappropriate for the motor shield you have? We can't guess these details,
you have to provide them.