I bought about 20 rolls of this stuff. I have shot it with both a Mamiya RZ and Hassy 500cm, and I have gotten this black line with both of the cameras. It has happened when developing at school and here at home, so I am ruling out that my tank is messed up, and that the camera has a light leak. I have shot around 3 rolls of this film without any problems, and have shot various rolls of print and slide film(color) and the line hasn't appeared. I am using d76 1:1 in a paterson tank. Anyone have any ideas as to what could be causing this?