Every time I develop a western blot film it's stained black everywhere that I can't see any band at all. After adding the pri antibody, i wash the membrane 5X and then add the sec antibody and wash again. Then i'll develop the film using the some substrate. The thing is, after adding the substrate, my membrane develops the bands that I'm interested in obtaining, but when I develop it on a film the whole film's stained black such that the bands cannot be observed. Anyone else has this prob and any recommendations?