First, if it is available in 6.3.4, use bljython instead of jython.
It looks like the script is unable to find jython at all.
What does the jython script look like (does it have env at the top)? If the script starts with "/usr/bin/env jython", try changing that to a direct reference to jython (/usr/nsh/jython/jython)
If that doesn't work, what is the path of the process that is running nsh scripts (create a simple nsh script job to echo $PATH)?
Finally, put a print "hello world" at the second line of the jython script to verify that the script is actually being called.
i just found out that it had to do with the transfer of the files, in ASCII rather than in binary. Thanks for the help.