What else do I have to put in this script to make it work?

local isOpen = true

function open()
    isOpen = true
    script.Parent.D3.Transparency = 0
    script.Parent.D3.CanCollide = true 
    script.Parent.D4.Transparency = 0
    script.Parent.D4.CanCollide = true 
    script.Parent.D1.Transparency = 1  
    script.Parent.D1.CanCollide = true 
    script.Parent.D2.Transparency = 1  
    script.Parent.D2.CanCollide = true
end

function closed()
    isOpen = false
    script.Parent.D3.Transparency = 1
    script.Parent.D3.CanCollide = true 
    script.Parent.D4.Transparency = 1
    script.Parent.D4.CanCollide = true 
    script.Parent.D1.Transparency = 0  
    script.Parent.D1.CanCollide = true 
    script.Parent.D2.Transparency = 0  
    script.Parent.D2.CanCollide = true
end

function onClicked()

    if isOpen == true then closed() else open() end

end

I want CanCollide on at all times
D1,D2,D3 and D4 = Door 1, Door 2, Door 3 and Door 4.