Why does the CFrame animation teleport?

for i = 0.001, 0.1, 0.001 do
    game.Workspace.Door.CFrame = game.Workspace.Door.CFrame * CFrame.new(Vector3.new(0,0.1,0))
    wait() 
    end
    end

    wait(5)

    for i = 0.001, 0.1, 0.001 do
    game.Workspace.Door.CFrame = game.Workspace.Door.CFrame * CFrame.new(Vector3.new(0,-0.1,0))
    end

So everything works until the door should go back, it just teleports back to the first position without any animation. Does anyone know why this happens?

Thanks for the help, Xsodar