Stops working after 3 clicks..?

I give full credit to "RoRecords" for part of this script.

Anyways, when I click the "Down" button more than 3 times, it stops working after 3 clicks...? Why?

script.Parent.Down.MouseButton1Down:connect(function()
    if #buttons > 6 then
        if scrolled < #buttons + 6 then
            for i,v in pairs(script.Parent.MainFrame:GetChildren()) do
                v.Position = UDim2.new(0,0,0,v.Position.Y.Offset - 100)
            scrolled = scrolled + 1
    end
        end
            end
end)
script.Parent.Up.MouseButton1Down:connect(function()
    for i,v in pairs(script.Parent.MainFrame:GetChildren()) do
    if scrolled > 0 then
        v.Position = UDim2.new(0,0,0,v.Position.Y.Offset + 100)
    scrolled = scrolled - 1
    end
    end
end)