Inaccurate Joystick readings when using motor shield.

Hi,

I am using a Arduino UNO to control motors based readings from joystick control.

For testing purposes I created two independent sketches. One for the joystick movements and one for the motors. They both work just fine.

The trouble comes in combining the sketches into one. Once the motors are activated my readings from the Arduino changed substantially.

What am I doing wrong?

I am using an Arduino UNO, Adafruit motor shield and regular joystick control.

I will post an image later on today.

Thanks in advance.