tkSnack pitch() for frequency estimation

[Justin Shaw]

I am using the tkSnack library to estimate the frequency from a sound file.
The pitch seems to drop down an octave at 400 Hertz. For example A~440
Hertz comes out at 220 Hertz. When I use the maxpitch and minpitch options
to limit the response to say 380 - 460 the result is all zeros.

Any ideas on how I can estimate the pitch of a sound up to 880 Hertz (with
tkSnack or not)?

Thanks
Justin Shaw