Problem with 9v battery

Hi, i have an unusual problem whith my arduino uno. I'm creating a robot so I use a 9v battery. My program doesn't work when i'm using my 9v battery but he runs normaly when the arduino is connected to my laptop with USB.

I tried different program so i'm sure that the trouble comes from my arduino. Do you have an idea ?

Thanks

If it is one of those small rectangular PP3 9V batteries then the problem is almost certainly that it cannot provide enough current to run your robot motors/servos.

Steve

It can't be that because i tryed different 9v batteries and because i use another battery for the motors. I have also noticed that the yellow led with a "L" on the arduino was running differently when the arduino was connected to the laptop.