Hi @Anonymous,
I spent some time with your model. I noticed a couple of things that confused me. I'm curious about that sketch - all the lines are fully constrained, yet I don't see any constraints or dimensions. Second, the sketch is slightly offset from the global coordinate system, which, I think also confuses the loft mapping process. So, I would maybe consider starting over with that sketch, and make sure that everything is nicely symmetric before you start. Also, there is a bit of an inherent point mapping challenge here - you have 3 points on the bottom profile that need to map to only 2 points in the top profile, and it's not clear to me even how that mapping should be done.
I made a screencast (with audio) showing some of this, and another way to attack the problem, and I'll post it as soon as it finishes processing
Hope it helps,
Jeff
Jeff Strater
Engineering Director