I've just installed a standard macppc/netbsd 3.1 from a CD and now I'm 
installing binary packages via pkg_add. I defined a

PKG_PATH=ftp://ftp.
de.netbsd.org/pub/pkgsrc/packages/NetBSD-3.1/macppc/All

if I add a 
binary like

pkg_add -v kdebase

......................................
Warning: package `ftp://ftp.de.netbsd.org/pub/pkgsrc/packages/NetBSD-3.1
/macppc/All/kdebase-3.5.4.tgz' was built for a different version of the 
OS:

Why is that and what can I do about it?

Ciao
Vittorio