Hi Heiner, yes could you please post the 3DM file with your sweep curves in it so I can try to repeat the sweep over here and try to figure out what's going wrong?

It could be some bug in the profile direction matching mechanism inside the sweep function. But I can't really tell without being able to try the sweep over here.

One workaround for the time being might be to just leave out the middle profile curve and only do the sweep by selecting the first and last profile curves only.

If your profile curves are made up of sub-segments it could also be that you're getting some unwanted segment-to-segment matching, and you may need to get the segments to be simplified into one single curve rather than a bunch of smaller segments by using something like the Rebuild command (http://moi3d.com/3.0/docs/moi_command_reference10.htm#rebuild) - the segmentation structure of the profile curves would be one of the things I would have looked at in the 3DM file if that was available, you can't really see many types of inner structural details like that from a screenshot alone.

- Michael