Ardumoto Motor Driver Shield

I have zumo chassis kit which I'm trying to connect with ardumoto motor driver shield. I'm using arduino mega2560. I have connected mega through USB and it's on. But when I attach the shield mega stops responding! There's no single blink from on/TX in mega after connecting to shield. But when removed again mega starts responding. The motor A is connected between 1 & 2 on the terminal and 3 & 4 for motor B. The VIN on the shield is connected to the 1.5vx4 AA batteries from the kit. I have powered the mega through the USB. I'm also using a PIR sensor.

Hi, Is this the motor shield?

//learn.sparkfun.com/tutorials/ardumoto-shield-hookup-guide

I'm not sure if it is pin out compatible with the mega, it is shown connected to a UNO controller. You will have to check diagrams for pin for pin compatibilty.

Tom.... :)