Help with a paintbrush?!

I want the paintbrush to paint Output says Players.Player1.Backpack.Paintbrush.LocalScript:18: attempt to index global 'Painbrush' (a nil value).In don't know what that means so also if you can help can you tell me what that means?

Colors = Red
Colors1 = Green
Colors2 = Blue
Colors3 = Purple
Colors4 = Black 
Player = game.Players.LocalPlayer
Paintbrush = script.Parent
mouse = Player:GetMouse()
function Paint()
if Colors == Red and Colors1 == Green and Colors3 == Purple and Colors4 == Black then
P = Instance.new("Part", Workspace)
P.FormFactor = "Plate"
P.BrickColor = BrickColor.new(math.random(math.random(math.random(math.random(math.random())))))
print("Activated Colors")
end 
end

Painbrush.Activated:connect(Paint)