You haven't given us any information yet. How many groups have you shot? If only one at each distance, you know nothing. It will have to be repeated to be sure. I am assuming you are not adjusting the elevation on the scope between ranges, (no real reason to at those distances), so cant will not be the reason. I'll bet it is your shooting. You may have held the rifle differently at each distance, or let the rifle recoil differently, or had a different cheek weld, etc..
Give us something to chew on, then we will have a better idea.