In my case I had an Ubuntu Server 9.10 i368 running mldonkey-server, and a client with Ubuntu Desktop (x64).
I could see downloads on the web interface, but I couldn't on KMLDonkey.
Both computers have a fresh install of Ubuntu.
I post this, just in case someone has the same problem.
I fixed the problem by removing ~/.kde/share/config/mldonkeyrc and reinstalling KMLDonkey.
I had the same problem on 9.10.
In my case I had an Ubuntu Server 9.10 i368 running mldonkey-server, and a client with Ubuntu Desktop (x64).
I could see downloads on the web interface, but I couldn't on KMLDonkey.
Both computers have a fresh install of Ubuntu.
I post this, just in case someone has the same problem. share/config/ mldonkeyrc and reinstalling KMLDonkey.
I fixed the problem by removing ~/.kde/