What is wrong with this colour changing script?

This is supposed to change the colour of a part depending on the mode, but doesn't.

local Colors = {BrickColor.new("Brown"), BrickColor.new("Dusty Rose"), BrickColor.new("Dark stone grey"), BrickColor.new("Med stone grey")}
local mode = script.Parent.Mode

function MakeSpark(pos)
    local effect = Instance.new("Part")
    effect.Name = "Effect"
    effect.Anchored = false
    effect.CanCollide = false
    effect.Shape = "Block"
    effect.formFactor = "Custom"
    effect.Material = Enum.Material.Plastic
    effect.Locked = true
    effect.TopSurface = 0
    effect.BottomSurface = 0
    effect.BrickColor = Colors[1]
    -- From here 
    if mode.Value == 1 or 2 then 
        effect.BrickColor = Colors[1]
    elseif mode.Value == 3 then
        effect.BrickColor = Colors[2]
    elseif mode.Value == 4 then 
        effect.BrickColor = Colors[3]

    end  
    -- To here, doesn't work
    effect.CFrame = CFrame.new(pos)
    effect.Parent = game.Workspace
end

Thanks.