What's happening, specifically? Is it not even picking prop types? Or is it not allowing you to lift them on the mouse click, or what?
Maybe there's something funky about using Vec3 p or something like the p.z needs to be greater or something? The index example just uses "GetMousePosition." If it's not picking prop types I've sometimes seen it written like: if (camera:Pick(p.x,p.y,pickinfo,pickradius,true,Collision.Prop)) then...
local p = window:GetMousePosition()
if (camera:Pick(p.x,p.y,pickinfo,pickradius,true)) then