Hi,
I installed MLDonkey. It seems to work fine, here what is says:
[mldonkey@localhost mldonkey]$ mlnet
Resolving [localhost] ...done
Using threads
Network Global Shares registered
Network Open Napster registered
Network Gnutella registered
Network G2 registered
Network Fasttrack registered
Network BitTorrent registered
Network Donkey registered
Network Soulseek registered
LOADING SHARED FILES AND SOURCES
Network.load_complex_options not implemented by BitTorrent
Network Soulseek disabled
Network Donkey enabled
Network BitTorrent enabled
Network Fasttrack disabled
Network G2 disabled
Network Gnutella disabled
Network Open Napster disabled
Error loading ./comments.met: Sys_error("./comments.met: No such file or directory")
For host 66.98.194.26 port 3306
+++ Exception BEFORE CONNECT connect failed: Network is unreachable
For host 82.64.235.58 port 4661
+++ Exception BEFORE CONNECT connect failed: Network is unreachable
For host 213.23.177.250 port 4242
+++ Exception BEFORE CONNECT connect failed: Network is unreachable
Network is unreachable : connect
chat_app_host=localhost chat_app_port=5036
SHARING ./incoming PRIO 0
QUERY URL http://ocbmaurice.dyns.net/pl/slist.pl?download
QUERY URL http://members.lycos.co.uk/appbyhp2/...es/contact.ocl
Welcome to MLdonkey client
Check http://www.mldonkey.net/ for updates
To command: telnet 127.0.0.1 4000
Or with browser: http://127.0.0.1:4080
Welcome to MLdonkey
SAVING SHARED FILES AND SOURCES
SAVED
Network.save_complex_options not implemented by BitTorrent
Options correctly saved
Core started
Disabling output to console, to enable: stdout true

That should be fine, right?
But when I start Sancho it says:
Core not found! localhost:4001 does not accept conections (core not found), try again?

What does that mean?
In the download.ini file from MLDonkey I set gui_port=4001 so it should work!
Please help me!
Thanks

...any firewall configured blocking a range of address ports ?

I have exactly the same problem. Tried with firewall accepting those ports but no.

When I type in terminal :
telnet localhost 4000

and then run Sancho, everything is OK.

I found the problem, and fixed it like this (there might be another way too):

1. In terminal :
telnet localhost 4000

2. run Sancho

3. select Tools -> Preferences -> sancho

4. in tab General, you can see "Optional core executable:" and add there the full path to your file "mlnet",
for example /home/user/MLDonkey/mlnet

You can also check the "Kill core on exit" if you want to. Exit the sancho and kill the MLDonkey core, and try again to run sancho.