50D Error 01?

Hello! I have a 50D that I bought off a friend a few months ago. I've been using my EFS 18-55mm from my older rebel until I could afford a new lense, but suddenly I'm getting an Error 01 code saying that the camera cannot communicate with the lense.

The lense works fine on the rebel, and the 50D works fine without a lense (or with a peice of plastic between the sensors to trick it, rather!). We tried cleaning it, updated the firmware... different batteries, different memory cards... nothing works.

Any thoughts? I will just end up buying a new lense... but want to make sure there's nothing else I can try first (and that it's not something to do with the body that needs fixing).

Lastly, rec's on a good basic lense for this model?

TIA!

It doesn't sound like a lens issue (if it works fine on your Rebel) so I think all you can reasonably do is make sure all the contacts in the camera spring out properly (aren't stuck down even a little bit) & are clean which you've already done. Aside from that you could have a go at resetting all camera & user settings but suspect you're pushing the proverbial uphill with a pointed instrument. It's likely a Canon repair needed - is it still in warranty?