Thanks to all who tried to help.  Most suggested the obvious (for obvious
reasons) that the job card must not be valid.  The problem actually was
much deeper than that.  Since we have Vesoft Security, I tried disabling
all security on a test system and produced the same results.  I got
desperate at this point and called the Response Center (that was not meant
in a bad way, my dealings with them are generally very good, I just like to
figure out problems myself).  They said the site stream command is not
supported, and they were going to check to see if it is supported on a
later patch release of 5.5.

With that avenue exhausted and no hope in site (no pun intended), it
occurred to me that we are using a facility of Vesoft Security that does
procedure exits to validate network logons.  I disabled this feature and
the site stream command worked.  I placed a call to Vesoft, they gave me a
documented parameter to add to my HELLO file, and now the site stream
command works.

It would have been nice to see a more meaningful error message, not "NO
:JOB OR :DATA COMMAND FOUND".  But then, perhaps that is just a good
security feature.