ADT 1.22 Difficulties - what's wrong?

[William Hubbard <kwooda@azstarnet.com>]

I have an Apple II+ and an Apple IIe and am attempting to use ADT v1.22
to transfer disk images to an old PC/XT.  I have successfully installed
(several times - and validated the installation) ADT on the Apple II's,
and I can issue the Directory command to get a directory of the PC from
the Apple, but the PC reports an ERROR: Unknown Command: 00.  Also, if I
try to Send a disk image to the PC, the Apple says it is Testing Disk
Format, then the PC creates a file with the name I gave, and then the
Apple reports ERROR: FILE DISK1.DSK <bunch of garbage characters here>
ANY KEY?  I have tried just about every cable configuration I can think
of and just about every combination of switches possible on the Super
Serial Card, yet I get the same results.  I am using the same SSC
between the Apple II+ and the Apple IIe, and get identical results on
both machines, so it seems to me the problem must be with the SSC.  I
have no manuals for the SSC (only what I have managed to find on the
Web), so am flying somewhat blind.

Any suggestions?

Thanks,
William Hubbard
kwooda@azstarnet.com