Continuous laser resource in 1.5.2

I managed to implement Derk Adams's resource into 1.5.0, but now that I've switched to 1.5.2, the laser beam shows up as flat black. Is this something to do with 1.5.2, or have I unwittingly broken the resource myself?
Thanks in advance.

EDIT: Upon further testing, the beam actually changes colour and transparency based on a few things. If aimed at a point within range (maxRange defined in laserImage), the beam is black, growing more transparent as time goes on (I think that functionality is intended). If aimed at, for example, the sky, or any other point outside the maximum range, the beam is flat white with no transparency.