Hey zim,
Its hard to tell from the screenshot, but i can see a couple rules to follow from it.

The "base" curve should be placed with the object to flow as you want it to end up on the surface. So if you look at frenchys image, his straight curve is laying directly at the base of the object. Yours seems to be situated some distance away? The flow calc will read this distance.

The other is the orientation. It will be best to have things pointed "up" to do the flow...(up being the z axis).