Problems with ir laser and weapons lights

[delta90 10]

Hi everybody! :)

I've got a problem with the IR LASER and the WEAPONS LIGHTS mounted on the default rifles (FN Scar, M4).

Sometimes it works, sometimes it doesn't!

I push "L" again and again but the light doesn't often turn on.. I've also tried to change the key but nothing happens..

What might be the problem?

Ps: I haven't mods mounted in the game.

thanks!!! :)