hum, that is very strange. Can you email us more info about your setup? I am guessing you have an entry for your module in videomappings.cfg already? One possibility is that on some machines (MacOS, Windows), the camera drivers get confused when trying to select among several video modes that only differ by their frame rate. This is not a problem when using guvcview, webcamoid, etc but it is a problem when using the Qt camera stack, which we use in the inventor. So maybe disable in videomappings.cfg any other modes that have the same output resolution but different frame rates.