This could be either a LED positioning issue or the PCB is not aligned with the axis of the gun.
Its possible to tell by looking at the Y readout in the config utility after clicking on "read data".
If you move the gun to the bottom of screen, you can see the reading decrease. if it is getting to 10 or below before you reach the bottom of the screen, then its a problem with PCB alignment or too close.
If it is well above 10 but then suddenly goes to blanks, then its losing the LED before going out of physical range, so the LEDs are blocked or not angled down enough.
Also, the utility will display an error message if calibration fails.