How to install openjdk-7-jre on Debian 6.0.6 or 6.0.7

openjdk-7-jre will fail to install on Debian 6.0.7 (or any stable version) with the following error:

E: Unable to locate package openjdk-7-jre

The steps to install openjdk-7-jre are the following :

• Go into Administration > Software Sources
• Remove (uncheck) all software sources (including CD-ROMs) :
• Add these two software sources :
  • deb http://ftp.us.debian.org/debian/ sid main
  • deb-src http://ftp.us.debian.org/debian/ sid main
• proceed with installation