Updating N900

ERROR: Nokia N900: NO_PUBKEY ADB4438160A655EF

When running an apt-get update on N900, I got the following  error:

Nokia-N900:~# apt-get update

W: GPG error: https://downloads.maemo.nokia.com ./ Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY ADB4438160A655EF

W: You may want to run apt-get update to correct these problems

running update again was of no use with the same error

Tried importing the key

Nokia-N900:~# gpg --keyserver subkeys.pgp.net --recv-keys ADB4438160A655EF

gpg: directory `/root/.gnupg' created

gpg: can't open `/gnupg/options.skel': No such file or directory

gpg: keyring `/root/.gnupg/secring.gpg' created

gpg: keyring `/root/.gnupg/pubring.gpg' created

gpg: requesting key 60A655EF from hkp server subkeys.pgp.net

gpgkeys: key ADB4438160A655EF not found on keyserver

gpg: no valid OpenPGP data found.

gpg: Total number processed: 0

not worked

So after trying this, I disabled following source in /etc/apt/sources.list.d/hildon-application-manager.list,

deb https://downloads.maemo.nokia.com/fremantle1.2/ovi/ ./

and its done

Reading package lists... Done

Some Optional repos

deb http://repository.maemo.org/ fremantle/sdk free non-free

deb-src http://repository.maemo.org/ fremantle/sdk free

deb http://repository.maemo.org/ fremantle/tools free non-free

deb-src http://repository.maemo.org/ fremantle/tools free

deb http://repository.maemo.org/ fremantle/4bc37c7c77ebe90177c050b805a8dc79 nokia-binaries

#deb http://repository.maemo.org/extras/ fremantle free non-free

#deb-src http://repository.maemo.org/extras/ fremantle free

#deb http://repository.maemo.org/extras/ diablo free non-free

#deb-src http://repository.maemo.org/extras/ diablo free

#deb http://repository.maemo.org/extras/ gregale free non-free

#deb-src http://repository.maemo.org/extras/ gregale free

deb http://ftp.de.debian.org/debian lenny main

#deb http://repository.maemo.org/extras-devel/ fremantle free non-free

#deb-src http://repository.maemo.org/extra-devel/ fremantle free non-free

Add Extras, Extras-Devel and Extras-Testing

Add Repository from following link.......better brows from N900 and then click links 

http://www.nokiadistrict.com/repositories-extras-extras-devel-and-extras-testing-for-nokia-n900/