Robot Not Recognized

Hi -- My son and I put together the Kit #1342, and when we plug it into the computer, it's not recognized. We tried Pickaxe Editor on Windows, and AxePad on a Mac. None worked. We also made sure to download the driver for the cable, and confirmed that the batteries were new. We also tried pressing the reset button each time. 

We went out and got a multimeter, to try to troubleshoot, but we really don't know what to test. 

Any ideas on breaking this down into smaller tests? To try to figure out what's not happening? 

Thanks much for any help!

- David