Unable to Cast Value to function?

So I was working on a Grow Script, but then It wouldn't let me TweenPosition a frame, I did everything right. It was in a local script. So I don't know what went wrong.

script.Parent.OnClientEvent:Connect(function()
	local SP = script.Parent.Parent
	local plyr = game.Players.LocalPlayer
	local OutPut = ((plyr.leaderstats.Rebirths.Value + 1) * 1000) - plyr.leaderstats["Player Size"].Value
	SP.Notificat.TextLabel.Text = "Sorry, you need " .. OutPut .. " more Speed to Rebirth."
	SP.Notificat:TweenPosition(
		UDim2.new(0.348, 0,0.206, 0),
		Enum.EasingDirection.InOut,
		Enum.EasingStyle.Back,
		0.3,
		false,
		0
	)
	wait(1)
	SP.Notificat:TweenPosition(
		UDim2.new(-1.348, 0,0.206, 0),
		Enum.EasingDirection.InOut,
		Enum.EasingStyle.Back,
		0.3,
		false,
		0
	)
end)