Having an odd problem with a boundary surface that is currently built OK,
If I edit the boundary and choose OK without changing anything, it fails to build - attempting to recreate the surface just gives me a please check input curves. I can't understand how it's successfully built, yet won't rebuild in the same state!
Anyone have any ideas on this one? Unfortunately we cannot contact the original contractor who built this surface...
That sort of thing can happen if you made any up-stream edits while not using the "verification upon rebuild" option. In my experience, this shows up if something upstream changed, but a real rebuild wasn't done, preventing the feature from failing until truly rebuilt (such as, by an edit to the feature itself). Try to roll back until just before the feature and whether a new boundary surface will function. Some features break with no visible reason--especially within surfacing tools.
The boundary surface may rebuild successfully when you edit the feature and reselect the curves. Solidworks files can die in their sleep, rebuild today and fail tomorrow. Subsequent trims and knits will vanish without a trace.
Without seeing the file it is hard to troubleshoot. Is it possible for you to post this file? If so you can edit your original post and add it there or use the "Use advanced editor" link in the upper right corner of the reply box.