When you draw anything, you have to specify the image's size, giving the distances of the sides of a rectangle which contains that image.
For example, if I had a 900 x 900 image (including white space), then the SetGraphicRect function would have (0, 0, 900, 900) because Danmakufu calculates images, along with some other things, by (left side, top side, right side, bottom side). SetMovePositionRandom01 is another example.
If your image is tiled, then most likely the sides you specified are wrong. Hmmm.... did you copy the same code for @BackGround and put it in @DrawLoop, except change the names of the images?