That projector has no lens shift meaning it needs to be hung at a specific height relative to the screen. In tech speak that is a fixed offset. On page 16 of your user manual it gives you the heights. In your case it is a little more than .6 of a foot above the top of the screen image. That is measured center of the lens to the edge of the image. You need to find a projector mount that will hang the projector at the exact height. Those would be ones with a variable down pole. I like Chief Mounts.