Why isn't the TweenPosition function working like it should in my script?

I am trying to make a box fly onto the screen with tween position.

I have recently run into an error that has puzzled me for quite some time now and after multiple attempts to fix my script, I decided to ask you guys on scripting helpers why my script isn't working the way it should.

Here is my script,

script.Parent.Position = UDim2.new(0.25,0,1,0)
script.Parent:TweenPosition(UDim2.new(0.25,0,.25,0), "Quint", "In", 2)

As you can see, this script is a child of the object I want to animate, a frame, but instead of it working I get this error,

20:21:09.874 - Unable to cast string to token
20:21:09.875 - Stack Begin
20:21:09.876 - Script 'Players.Player1.PlayerGui.MACROS.login.box.Starter', Line 2
20:21:09.877 - Stack End

I can't seem to figure out what this error message means so I am in need of help. Thanks.