I had the same problem as Michele at SFO. My roll-on bag was too deep for the belt! I was able to shove it into the cut-out hole by taking a few items out of the outside pockets. I've found that a backpack style bag works better for fitting into the xray belt and the size-wise things found by the gates - where I have had an attendant tell me to put my bag into the device to see if it fits. It did, since it was soft and I could squish it into the space!

A bigger problem one might have is being under the weight requirment for carry-ons. Alitalia only allowed us 11 lbs last year. Be sure to check with your airline for their current maximum weight requirements.

Best of luck with carry-on luggage! Kristy S.F.