How to make a script to open and close an elevator door?

Here's the script:

while true do

game.Workspace.RDoor.CanCollide = true

game.Workspace.RDoor.Transparency = 0

wait(15)

game.Workspace.RDoor.CanCollide = false

game.Workspace.RDoor.Transparency = 1

wait(20)

end

I'm trying to change the transparency and turn cancollide on and off to make it seem like the door is opening and closing, but it's not working. What do I have to add to the script?

maybe change game.Workspace.RDoor to workspace:FindFirstChild(“RDoor”,true) for each line