If you are using runfm to produce PDF output, some of the possible errors you can get might not be documented at all for the FDK function involved, so you will have to do the usual type of troubleshooting for PDF problems. For example, sometimes Distiller does not like a particular graphic. If you get an error when you make the PDF manually in FrameMaker (by printing to the Adobe PDF printer, not via SaveAs PDF), try cutting the file in half, and see which part still has the problem. Repeat until you identify the exact point of trouble.
When Distiller makes a PDF, it always writes the output to My Documents for the logged-in Windows user. If Distiller fails, an error message might not be returned from the FDK, and the output file will simply not be present. When Mif2Go does find the file, Mif2Go moves it to the destination you specified.