Why this debounce is not working?

local credits = false
local SG = script.Parent.Parent.Parent
local debounce = false

script.Parent.MouseButton1Click:connect(function ()
    if credits == false and debounce == false then
        credits = true
        debounce = true
    end 
    if credits == true and debounce == false then
        credits = false
        debounce = true
    end
    if credits == true and debounce == true then
        SG.Credits.Visible = true
        for i = 1, 14 do
            SG.Credits.Position = SG.Credits.Position + UDim2.new(0.05,0,0,0)
            wait(0)
            if i == 14 then
                script.Parent.Text = "Close Credits"
                debounce = false
            end
        end
    end 
    if credits == false and debounce == true then
        for i = 1, 14 do
            SG.Credits.Position = SG.Credits.Position - UDim2.new(0.05,0,0,0)
            wait(0)
            if i == 14 then
                script.Parent.Text = "Credits"
                SG.Credits.Visible = false
                debounce = false
            end
        end
    end
end)

So, the debounce here is to avoid that people that clicks a milion a times per second to open something and bugs the gui, right? Well im using debounce, but when i click alot of times on the button, the gui bugs. Whats the problem?