ppa directory disappeared

[Joep L. Blom]

I wanted to update my system and the package manager said:
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http://ppa.launchpad.net/gnokii/ppa/ubuntu/dists/lucid/main/binary-amd64/Packages.gz 
  404 not found
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When I looked in the directory the only distribution available was maverick.
I had selected the best mirror for me which is: 
http://ubuntuarchive.eweka.nl.ubuntu.
Can anybody tell me how I can change this strange behaviour?
I use Lucid 10.4 LTS and don't want to change.
Joep