Batch Converter: What do status -2000 and status -210 mean?

What do these two codes from Batch Converter mean?

Unable to save c:\jnk\ref.dgn to c:\jnk\out\ref.dwg in DWG format, status -2000.
Unable to save c:\jnk\other 1.dgn to c:\jnk\out\other 1.dwg in DWG format, status -210.