apt-get error : Temporary failure resolving ...

[KernelMind]

Hi ALL,
In debian lenny, I have the following error in apt-get (through proxy):

Temporary failure resolving 'security.debian.org'
Temporary failure resolving 'security.debian.org'
Temporary failure resolving 'volatile.debian.org'
Temporary failure resolving 'volatile.debian.org'
Temporary failure resolving 'http.us.debian.org'
Temporary failure resolving 'http.us.debian.org'
Temporary failure resolving 'http.us.debian.org'
Temporary failure resolving 'http.us.debian.org'
Temporary failure resolving 'http.non-us.debian.org'
Temporary failure resolving 'http.non-us.debian.org'
Temporary failure resolving 'http.non-us.debian.org'
Temporary failure resolving 'http.non-us.debian.org'
Temporary failure resolving 'packages.dotdeb.org'
Temporary failure resolving 'packages.dotdeb.org'
Reading package lists... Done
W: Failed to fetch packages.dotdeb.org/dists/stable/Release.gpg Temporary failure resolving 'packages.dotdeb.org'
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Note: This is not the exact error, because of : " 1. You are only allowed to post URLs to other sites after you have made 15 posts or more."
Please help me!

[KernelMind]

My sources.list is ok.
And I wrote the proxy in bash.bashrc.