I found the problem. The preference is:
Windchill Workgroup Manager, Server, Checkin, Collector, Include dependent CAD Document, Required.
On one of our server this was set to None.
David Haigh
Phone: 925-424-3931
Fax: 925-423-7496
Lawrence Livermore National Lab
7000 East Ave, L-362
Livermore, CA 94550