Vacuum Cleaners Discussions

Hi, We have a Dirt Devil Jaguar II. I can't tell you exactly how old it is but it is definitely a few years old. We have had trouble replacing the bag in the past. This time when we put in the new bag, the door doesn't close completely and there is virtually no suction and a whistling noise. The motor runs fine (and there is suction) when the bag is not present. I have tried two separate bags (and the bags are the right brand) but both produce the same sound. The sound doesn't appear to be coming through the improperly closed door. It seems as though there is some kind of lack of fitting between the hose and the bag itself, but we can't figure it out. Has anyone ever had this problem with a dirt devil? Any ideas about what to do? Thanks a lot!