curtain simulation

Hi I'm trying to achieve the effect of a curtain that moves in the Y-axis. Essentially the movement of the curtain would follow the profile of a sine curve. In order to do this I mapped a sine curve along a curve and for some reason the curve is not closed and I tried interpolating the end points of the curve to close it, but it does not seem to work. It would be great if anyone can help. Thanks!

curtaindefinitions. ghcurtains.3dm