Autodesk Inventor

[#1]

I'm  trying to add a piece of steel to a frame I created several days ago.  As you can see in the pic, I had no trouble adding steel members and trimming them.  This morning, an attempt to add one more cross beam on the sketch line to the right, generated this error message.  I have attempted to place a member on several sketch lines in this assembly with the same results.  Has anyone seen this "unknown" error?

Restarting Inventor was unsuccessful.  I will try on a new assembly and see if I get the same results.

[#2 · Accepted solution]

Works fine everywhere else.  I think the skeleton became corrupted from some messing I did with it yesterday.  It will be quicker and less painfull to start over clean.  Thanks.