One thing you might try is makeing a batch file such as

:: rsh.bat

  echo %1 >> C:\look.txt 
  echo %2 >> C:\look.txt
  ...
[download]

Then try the perl script against the batch file instead of the rsh exe. This should at least confirm that the program is getting the parameters. Aside from that, as others have said, I would try using rsh from the same working directory from the command line and test it there as well.