Though I'd have your friend confirm that the redirection works correctly at the prompt.
FWIW, /bin/sh in any fairly recent HP-UX is something called a POSIX shell. It's quite a lot like bash, but not completely (in fact, you probably wouldn't even notice unless you do complicated shell programming). As evidenced by the name, it's the default shell. I really rather doubt the shell is interfering in file redirection like that, but it's probably worth a check. Redirection is easy to find in the man page.
Wade.