Environment set error when I run the Ftouch Utility on hpux

I have NATURAL v. 5.1.1 I’m trying to run the ftouch utility but I’m receiving an environment error.

bccdev2:/pgwsag/bccqam11/sag/nat/v51113/bin> ./ftouch lib=QAM11 convert

    FTOUCH UTILITY V 5.1.1 Pl 13   Software AG 2003

    Not able to find "NATDIR" and/or "NATVERS" environment variable!

    If you have set the "NATDIR" environment variable,
    please check that it does not contain invalid or 
    whitespace characters!
    "NATVERS" should only contain the NATURAL version