Does work.

This was happening when I was just goofing around with the in-game editor.

In your case, you have to place the laser-relay on the floor or on the roof
in order to make it possible to activate it with a laser... I know it looks
like the laser is touching it in your screen, but somehow it doesn't. =/

PortalCombat wrote:
Short answer: Because the PeTI instances are really badly made.

Yeah, I've come across some awkward situations like that:

http://www.steamcommunity.com/sharedfiles/filedetails?id=72496037

Even some of the official story mode chambers have instance bugs, like the hover glitch of the excursion funnel.