No Power to Pi

When I power up my GoPiGo with the battery pack it does not power the Raspberry Pi. I can get power to the Pi when I use power from the wall mount.

Second, I have it connected through wifi but the robot never responds to any commands.

I had the same problem and it was a weak battery pack. Add fresh batteries and it should work.

aarmau, couple of questions here:
Did you try to check the battery level?
When you say the robot never responds to any commands, which commands are you trying?