We edited a dwg file with Draftsight then tried to open it with Autocad LT 2002.  Autocad LT produced the error "AutoCAD LT Error Aborting - FATAL ERROR: Error code (0x645600005) c:\\program files(x86)\\common files\\autodesk shared\\acismobj15.dbx"

We also took a Draftsight edited dwg to Staples for plotting and they could not open it.  Are there known troubles with compatibility?