pkg_add: Error: package `squid-3.1.12nb1' was built with a newer pkg_install version

[Edgar Rodolfo <cybernautape%gmail.com@localhost>]

Hello my friend i have a error when i want to install some package,
for example squid, vlc
and other, i remember that two weeks ago, i did it and i did not see
the same error, help me please.
currently i have:

netbsd51# uname -a
NetBSD netbsd51.dominio.org 5.1 NetBSD 5.1 (GENERIC) #0: Sun Nov  7
14:39:56 UTC 2010
builds%b6.netbsd.org@localhost:/home/builds/ab/netbsd-5-1-RELEASE/i386/201011061943Z-obj/home/builds/ab/netbsd-5-1-RELEASE/src/sys/arch/i386/compile/GENERIC
i386
netbsd51#

look:

netbsd51# cat ./.profile
#       $NetBSD: dot.profile,v 1.18.34.3 2009/02/23 08:50:41 snj Exp $

export PATH=/sbin:/usr/sbin:/bin:/usr/bin:/usr/pkg/sbin:/usr/pkg/bin
export PATH=${PATH}:/usr/X11R7/bin:/usr/X11R6/bin:/usr/local/sbin:/usr/local/bin

# Uncomment the following line to install binary packages
# from ftp.NetBSD.org via pkg_add.
#export PKG_PATH=ftp://ftp.netbsd.org/pub/pkgsrc/packages/NetBSD/$(uname
-m)/5.0#/All

export PKG_PATH="ftp://ftp.netbsd.org/pub/pkgsrc/packages/NetBSD/i386/5.1/All";

export BLOCKSIZE=1k

export HOST="$(hostname)"

if [ -x /usr/bin/tset ]; then
        eval `tset -sQrm 'unknown:?unknown'`
fi

umask 022
#ulimit -c 0

export ENV=/root/.shrc

# Do not display in 'su -' case
if [ -z "$SU_FROM" ]; then
        echo "We recommend creating a non-root account and using su(1)
for root access."
fi
netbsd51#
netbsd51# cat ./.profile
#       $NetBSD: dot.profile,v 1.18.34.3 2009/02/23 08:50:41 snj Exp $

export PATH=/sbin:/usr/sbin:/bin:/usr/bin:/usr/pkg/sbin:/usr/pkg/bin
export PATH=${PATH}:/usr/X11R7/bin:/usr/X11R6/bin:/usr/local/sbin:/usr/local/bin

# Uncomment the following line to install binary packages
# from ftp.NetBSD.org via pkg_add.
#export PKG_PATH=ftp://ftp.netbsd.org/pub/pkgsrc/packages/NetBSD/$(uname
-m)/5.0#/All

export PKG_PATH="ftp://ftp.netbsd.org/pub/pkgsrc/packages/NetBSD/i386/5.1/All";

export BLOCKSIZE=1k

export HOST="$(hostname)"

if [ -x /usr/bin/tset ]; then
        eval `tset -sQrm 'unknown:?unknown'`
fi

umask 022
#ulimit -c 0

export ENV=/root/.shrc

# Do not display in 'su -' case
if [ -z "$SU_FROM" ]; then
        echo "We recommend creating a non-root account and using su(1)
for root access."
fi
netbsd51#

 I am using xfce4, i installed many packages using pkg_add, but i can
not install squid, and
other, what is my mistake?


-- 
Edguitar ;)
http://cybernautape.blogspot.com