I am practicing sweeps and am trying to do a fairly basic one. Essentially it is just two cylinders of equal radius (15mm) and heights 30 and 45mm with the centres separated by 90mm. I want to use a sweep to create a curved rib which runs between the tops of the cylinders. To avoid zero-thickness issues, I've created the rectangular profile for the sweep on a plane inside the short cylinder (10mm from its centre). The path is a line on the base which runs from that plane to a similar point inside the taller cylinder. I've attached two screen shots. Sweep1.jpg shows that this sweep works without the guide curve which is shown in orange. Now when I specify the guide curve, the sweep stalls about 5mm from the outside of the tall cylinder (sweep2.jpg). I've even removed the tall cylinder and the sweep still stalls at the same point. I also tried making the 3 parts of the guide curve into a single composite curve, but that didn't help. I can't see any reason why the sweep should not complete to the end of the path. Any ideas of what is going wrong here?