Help with core dump and gdb

I unzip'd some crash files and ran gdb:

   bigbox#  file *
   netbsd.6:      ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), statically linked, not stripped
   netbsd.6.core: data
   bigbox# ls -l
   total 139040
   -rw-------  1 root  wheel    8459982 Mar  6 19:00 netbsd.6
   -rw-------  1 root  wheel  133825044 Mar  6 19:00 netbsd.6.core
   bigbox# ls -l /net*
   -rwxr-xr-x  1 root  wheel  8459982 Mar  6 09:41 /netbsd
   -rwxr-x---  1 root  wheel  8459982 Mar  6 09:37 /netbsd.030607.debug
   -rwxr-xr-x  1 root  wheel  8412345 Sep 10 01:35 /netbsd.first
   -rwxr-xr-x  1 root  wheel  8189387 Sep  7 22:54 /netbsd.installed.3.0.1
   -rwxr-x---  1 root  wheel  8531836 Mar  6 09:41 /netbsd.second
   bigbox# gdb -c netbsd.6.core netbsd.6
   GNU gdb 5.3nb1
   Copyright 2002 Free Software Foundation, Inc.
   GDB is free software, covered by the GNU General Public License, and you are
   welcome to change it and/or distribute copies of it under certain conditions.
   Type "show copying" to see the conditions.
   There is absolutely no warranty for GDB.  Type "show warranty" for details.
   This GDB was configured as "i386--netbsdelf"...(no debugging symbols found)...
   "/var/crash/crash6/netbsd.6.core" is not a core dump: File format not recognized
   (gdb) bt
   No stack.
   (gdb) where
   No stack.
   (gdb) 

Where did I go wrong?

TIA,
Paul