Gmod aimbot

Hello, My name is Hunter and i am trying to create an working aimbot for GMOD. I began by looking into how to script with lua and came up with this

function aimbot() -- Starting the function
local ply = LocalPlayer() -- Getting ourselves
local trace = util.GetPlayerTrace( ply ) -- Player Trace part. 1
local traceRes = util.TraceLine( trace ) -- Player Trace part. 2
if traceRes.HitNonWorld then -- If the aimbot aims at something that isn't the map..
local target = traceRes.Entity -- It's obviously an entity.
if target:IsPlayer() then -- But it must be a player.
local targethead = target:LookupBone("ValveBiped.Bip01_Head1") -- In this aimbot we only aim for the head.
local targetheadpos,targetheadang = target:GetBonePosition(targethead) -- Get the position/angle of the head.
ply:SetEyeAngles((targetheadpos - ply:GetShootPos()):Angle()) -- And finally, we snap our aim to the head of the target.
end
end
end
hook.Add("Think","aimbot",aimbot) -- The hook will spam "aimbot" until it finds a target..

Whenever i try to use this in game i cant get it to work...Any advice or tips?