Calling the FaxSchedule() function on Windows 7 (x86) always returns 0xfffffff8 (FAX_ERR_BADFILE) and the fax doesn't get scheduled. The same call works correctly on Windows 2000, XP, Server 2003 and Server 2008. The fmf created appears to be fine (verified by renaming to .TIF and opening in a graphics viewer).
I also notice that the "sentinel" member of the APPINFO structure obtained from the call to FaxRegisterApp is set to an invalid value (0xbcbcbcdd) when called on Windows 7 - which may or may not be related to the FaxSchedule() issue.
Any advice would be appreciated.