If the developed film is blank but shows color staining and darkened edges, that points to unwanted light exposure rather than normal image exposure through the shutter. In a camera exposure, the film gate masks the edges of the film, so those edge markings would not be affected by overexposing a photo. When the edges are darkened or stained, it usually means light reached the film from somewhere other than the lens/shutter path. That suggests a light leak or that the film was exposed to light outside the camera’s normal operation. So this is less likely to be a simple exposure-setting mistake and more likely a problem with stray light reaching the roll.