I think pkgsrc doesn't support NetBSD 1.6 anymore?
I'm seeing this when trying to install BIND9 on an i386 NBSD 1.6 box :

/usr/bin/install -c -o root -g wheel -m 444 
/usr/pkgsrc/net/bind9/work/bind-9.4.1-P1/README /usr/pkg/share/doc/bind9
set -e; cd /usr/pkgsrc/net/bind9/work/bind-9.4.1-P1/doc && /bin/pax 
-rwppm                       -s ',.*xsl.*,,' -s ',Makefile.*,,' -s 
',.*\.pl,,'               . /usr/pkg/share/doc/bind9
pax: Unable to remove directory /usr/pkg/share/doc/bind9/./arm/ 
<Directory not empty>
pax: Unable to remove directory /usr/pkg/share/doc/bind9/./arm/ 
<Directory not empty>
pax: Unable to remove directory /usr/pkg/share/doc/bind9/./ <Invalid 
argument>
pax: Unable to remove directory /usr/pkg/share/doc/bind9/./misc/ 
<Directory not empty>
pax: Unable to remove directory /usr/pkg/share/doc/bind9/./misc/ 
<Directory not empty>
pax: Unable to remove directory /usr/pkg/share/doc/bind9/./ <Invalid 
argument>
*** Error code 1

Stop.
make: stopped in /usr/pkgsrc/net/bind9
*** Error code 1


Is there any way to force it to install?  The server's slated for an 
upgrade to 3.1 or 4 when it's released, but not for another month or 
three, and 'make update' removed bind9 that was previously installed. 
Backups are a last resort, I'd much prefer, if possible, to install the 
current version of bind9 (and clamav etc ...)

I have the current pkg_install
mail2: {72} pkg_info | grep install
pkg_install-20070813 Package management and administration tools for pkgsrc

If that makes any difference?