Why is this part going up but not going to the left?

Here is my script that I have problems with:

MiningArea = script.Parent.Parent.Parent
PartPos = script.Parent.Position
function CClone(Xadd, Yadd, Zadd) --Function
	local part = game.Lighting.Block:Clone()
	part.Parent = MiningArea.Blocks
	part.Position = script.Parent.Position
	script.Parent.Position = Vector3.new(PartPos.X + Xadd, PartPos.Y + Yadd, PartPos.Z + Zadd)
	wait(0.01)
end


CClone(0, 5, 0) -- Goes up by 5

CClone(0, 5, 0)

CClone(0, 5, 0)

CClone(0, 5, 0)

CClone(0, 5, 0)

CClone(0, 5, 0)

CClone(0, 5, 0)

CClone(0, 5, 0)

CClone(0, 5, 0)

CClone(0, 5, 0)

CClone(0, 5, 0)

CClone(0, 5, 0)

CClone(0, 5, 0)

CClone(0, 5, 0)

CClone(0, 5, 0)

CClone(0, 0, -5) --This goes up for some reason!

I added comments that tell you things. Please help me ASAP.

You define PartPos outside of the function, so it doesn't get updated.

Just define it inside the function.

function CClone(Xadd, Yadd, Zadd) --Function
    local PartPos = script.Parent.Position -- moved
    local part = game.Lighting.Block:Clone()
    part.Parent = MiningArea.Blocks
    part.Position = script.Parent.Position
    script.Parent.Position = Vector3.new(PartPos.X + Xadd, PartPos.Y + Yadd, PartPos.Z + Zadd)
    wait(0.01)
end

Also use local variables you savage