And if that isn't it follow this formula.
Your POI moves 1/4 inch at 100 yards but if your shooting at 20 yards which 1/5 of 100 yards your scopes POI moves to 0.05 per click at 20 yards. Take the amount you are off and divide it by 0.05 lets say your off 4 inches that would equal 80 clicks. If that doesn't work because your scope bottoms out then you will need to realign your scope on the mount and also check the mount to crossbow. Do the mounting holes look to be in the right place? Are there any bits of plastic or other material laying in the way of a good clean fit. Does anything look bent mounting plates and slides should be straight.
Clean it all up and reassemble it and try again.