apt-get failed to find any updates for Debian squeeze

# ls -F /etc/apt/
apt.conf.d/     preferences.old  sources.list     trustdb.gpg  trusted.gpg~
preferences.d/  secring.gpg      sources.list.d/  trusted.gpg  trusted.gpg.d/


# cat /etc/apt/sources.list
deb http://ift.tt/1A8DGsk oldstable main
deb http://ift.tt/1A8DGsk oldstable-updates main
deb http://ift.tt/A2rwP6 oldstable/updates main


# apt-get update
Hit http://ift.tt/1A8DJUX squeeze Release.gpg
Ign http://ift.tt/1A8DGsk squeeze/main Translation-en
Ign http://ift.tt/1A8DGsk squeeze/main Translation-en_US
Hit http://ift.tt/A2rwP6 squeeze/updates Release.gpg
Ign http://ift.tt/A2rwP6 squeeze/updates/main Translation-en
Ign http://ift.tt/A2rwP6 squeeze/updates/main Translation-en_US
Hit http://ift.tt/1A8DJUX squeeze-updates Release.gpg
Hit http://ift.tt/A2rwP6 squeeze/updates Release
Hit http://ift.tt/A2rwP6 squeeze/updates/main amd64 Packages
Ign http://ift.tt/1A8DGsk squeeze-updates/main Translation-en
Ign http://ift.tt/1A8DGsk squeeze-updates/main Translation-en_US
Hit http://ift.tt/1A8DJUX squeeze Release
Hit http://ift.tt/1A8DJUX squeeze-updates Release
Get:1 http://ift.tt/1A8DJUX squeeze/main amd64 Packages [6,527 kB]
Get:2 http://ift.tt/1A8DJUX squeeze-updates/main amd64 Packages [14 B]
Fetched 5,479 kB in 25s (213 kB/s)
Reading package lists... Done


# apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.


# dpkg -l libc6 | grep libc6
ii  libc6                                 2.11.3-4                     Embedded GNU C Library: Shared libraries


# lsb_release -a
No LSB modules are available.
Distributor ID: Debian
Description:    Debian GNU/Linux 6.0.10 (squeeze)
Release:        6.0.10
Codename:       squeeze


# w3m -dump http://ift.tt/1zoymOG | grep '2.11.3-4+deb6u4_amd64'
libc-bin_2.11.3-4+deb6u4_amd64.deb . . . . . . . . . Jan 28 01:26   732K
[ .. snipped ..]

Any insights?