Arduino WiFi Shield not communicating

I am using both the official wifi shield and the Uno R3.
Everything was working perfectly, although I did notice when I power them with a 9V battery through the 21mm plug instead of using USB. The WiFi shield may not power up all the time. And now, the WiFi shield doesn't connect to the network whether it's powered with USB or 9V.

I can still control the L9 on the WiFi shield.

However, even when I just use the ScanNetwork example sketch that comes with the library, the none of the L9/Data/Link/Error LED lights up on the WiFi board. And of course, it couldn't connected to the network.

The only two things I did between when it worked perfectly and failed completely, was I switched to 9V battery, and I tape the boards to my robot chasis. Could either of these have messed it up? How else can I trouble shoot this....... :astonished:

Everything was working perfectly, although I did notice when I power them with a 9V battery through the 21mm plug instead of using USB.

You noticed what?

Your not talking about one of those rectangular, overpriced, low current smoke detector style batteries, are you? They are useless for powering current hungry devices like WiFi shields.