error with dock4.0.1

Dear all,
               I have been using Dock 4.0.1 and am having problems with a few
 compounds.  Dock is breaking apart the starting structure and only docking a
 portion of the ligand.
 The error reported in the dock.out file was:
                                 WARNING shrink_list: No members provided
 This error occured when I ran Dock 4.0.1 on either a unix or linux platform.
 The starting structure was retinoic acid.  The same error occured for
 isoretinoin.  These were not the only cases. The starting structures were
 fine.  I also rebuilt these structures to make sure with the same error
 occuring.  I cannot find any information about this error in the Dock
 Can anyone tell me what this error means and how I can avoid it.
 Jerome Wielens