Lua help

Hi I am trying to make an AFK kicker but i keep getting errors


local function AFKKicker()	
	ply.butRelease = 0
	ply = player.GetAll()
	ply.butRelease = CurTime()
	if CurTime() - ply.butRelease < 5 then
	ply:Kick( "You were afk for to long" )
	end
end
hook.Add("PlayerButtonUp", "ButtonLetGo", AFKKicker)
local function AFKCheck()
	ply.butRelease = 0
	ply = player.GetAll()
	if (CurTime() >= ply.butRelease) then
		end
	end	
hook.Add("Think", "thinkhook", AFKCheck)

also i do not want some huge code you made or a download one i want someone to help me fix mine my error at the moment is
[ERROR] addons/brettscripts/lua/autorun/server/afkkicker.lua:6: attempt to call method ‘Kick’ (a nil value)

  1. v - addons/brettscripts/lua/autorun/server/afkkicker.lua:6
  2. unknown - lua/includes/modules/hook.lua:84

http://puu.sh/a5BwM/8feb17b31d.png

Please remake your thread in the correct section.