If you are doing everything correctly then it might be the proximity to the blueprint, I'm not sure how pp makes workshop items invalidaded but it could be the cause. Otherwise if you really don't know why the best I can do is refer you to a video tutorial on how to build it over again. See if this one is any help: https://www.youtube.com/watch?v=lYj6aGRDUYg (The plank is not necessary, just retried it from memory and it works fine)

yea but it doesn't work

See if you didn't miss any details, the laser needs to connect to every mirror before hitting the ground and the required speed set should be either -8000 or 8000

it doesn't work for me?

cool

thanks for the help

YOU are the best

tysm

thanks!