Tween Not Working-Unable to Cast Value to Function?

My GUI tween keeps coming up with the error Unable to Cast Value to Function. Any help to fix this issue would be much appreciated.

Here is my code:

local creditsButton = script.Parent.Parent:WaitForChild("CreditsButton")
local changelogButton = script.Parent.Parent:WaitForChild("ChangelogButton")
local playButton = script.Parent.Parent:WaitForChild("PlayButton")
local gameTitleLabel = script.Parent.Parent:WaitForChild("GameTitleLabel")


local function hidePlayButtonTween()

    playButton:TweenPosition(

        UDim2.new(1, 0, 0.326, 0), --End Pos
        "Out", --Easing Direction
        "Sine", --Easing Style
        1, --Time
        false, --Override Other Tweens
        false --Callback
   )
end



creditsButton.MouseButton1Up:Connect(hidePlayButtonTween)
creditsButton.TouchTap:Connect(hidePlayButtonTween)