[plt-scheme] Simple ffi problem

If I run the following code in DrScheme under windows:

    (module test-network mzscheme
            (require (lib "foreign.ss")) (unsafe!)

            (get-ffi-obj "scheme_security_check_file" #f
                         (_fun _string _string _int -> _void))

            )


I get the following error:

    ffi-obj: couldn't get "scheme_security_check_file" from #f (The specified procedure could not be found.; errno=127)


If I do the same under Unix (FreeBSD) I don't get the error message.  Is this a bug in mzscheme or am I doing something wrong?

I'm running version 349.100 on both systems, language level (module ...) on Windows, just using mzscheme on FreeBSD.

Thanks,

Evan