I'm in Panic mode! Help! Have had several intermittant rolls of 220 and 120 film be completely blank. 7 out of 11 in one job, 1 out of 4 another job,. Am now holding off any bookings until I find out what is wrong. The shutter is opening/closing fine when I take off back and chk. No lens cap. No flash attachment ( camera set on X) I recently purchased a used 220 back and 220 film ( in 30 yrs, have never used 220 before and am still trying to figure out why now that I see how I love the reduced amt. of time spent loading.reloading film!)) and this is when problem began, but it is also doing it when I switch backs during my shoot and use 120. I am using 1 yr. expired Kodak film, but have done that for yrs. with no problem.When I first used the 220 back, I had a bit of a glitch in that the camera seemed to lock or not advance after just exposing about 12 shots and I tried to force ( I know,,,wrong! ) the crank and ripped the film into. But after I seemed to get the feel for the 220, that didn't happen again. But now worse problem....absolutely completely blank entire rolls! Horrors. Now must do shoot over and am afraid to book new jobs. I use a cable release with Blad on tripod always. 60spd/4 aperture all shots. I read a suggestion that film loaded backwards would come out blank, but that when you took it out of the back it would be black. That has not been the case...It is not the black side showing. What could possibly be wrong???? This is NOT the season to discontinue photo shoots of children for Christmas. I'm a wreck trying to figure it out. Pls. don't say it could possibly be because film is 1 yr. expired (10/08) as I purchased 256 rolls! Need help quick.... Beverly p.s. the rolls that did turn out were fine....all images perfect exposures, etc. no overlapping either. I did have one of the first rolls of 220 I tried, to have a few blank frames, scattered thruout. I attributed it to me using 220 for first time and thought perhaps I had advanced it wrong somehow ( altho I can't figure how) Took me by surprise that you have to roll it for a bit longer just to get to the 1st frame. ....moreso than 120.