Problems when tweening frames where is the problem?

When I activate the function "In ()" it works partially perfect but in about 1 out of 5 cases only 2 of the buttons will appear and in 1 in 10 cases nothing will show up. Did I do something wrong and if so, what did I do wrong?

function functions.In()
	
	wait (0.05)
	
	script.Parent:WaitForChild("Left_BTN_2"):TweenPosition(UDim2.new(1, 0,0.017, 0), 'Out', 'Quad', 1)
	script.Parent:WaitForChild("Right_BTN_2"):TweenPosition(UDim2.new(1.4, 0,0.017, 0), 'Out', 'Quad', 1)
	
	wait (0.05)
	
	script.Parent:WaitForChild("Left_BTN_1"):TweenPosition(UDim2.new(0.869, 0,0.017, 0), 'Out', 'Quad', 1)
	script.Parent:WaitForChild("Right_BTN_1"):TweenPosition(UDim2.new(1.532, 0,0.017, 0), 'Out', 'Quad', 1)
	
	wait (0.1)
	
	script.Parent:WaitForChild("Center"):TweenPosition(UDim2.new(1.132, 0,0.017, 0), 'Out', 'Quad', 1)
	
end

function functions.Out()
	
	wait (0.05)
	
	script.Parent:WaitForChild("Left_BTN_1"):TweenPosition(UDim2.new(-0.607, 0,0.017, 0), 'Out', 'Quad', 1)
	script.Parent:WaitForChild("Right_BTN_1"):TweenPosition(UDim2.new(2.800, 0,0.017, 0), 'Out', 'Quad', 1)
	
	wait (0.05)
	
	script.Parent:WaitForChild("Left_BTN_2"):TweenPosition(UDim2.new(-0.738, 0,0.017, 0), 'Out', 'Quad', 1)
	script.Parent:WaitForChild("Right_BTN_2"):TweenPosition(UDim2.new(2.900, 0,0.017, 0), 'Out', 'Quad', 1)
	
	wait (0.1)
	
	script.Parent:WaitForChild("Center"):TweenPosition(UDim2.new(1.132, 0,3.8, 0), 'Out', 'Quad', 1)

end