I'm having developing problems with Neopan400, 120mm. I've developed a couple rolls of TX400 35 mm myself, that have turned out well, but I can't get the neopan 400 to develop. I'm using D-76 devloper at 80 degrees for 4 3/4 minutes. When I take the film out of the canister its grey with part of the image showing and the back of the film is still pinkish. And it is not transparent at all. Any ideas what could be wrong?