Possible reasons OTHER then that the person you are trying to get the file from is busy or gone offline:

- The ICS user - you may need to force your local IP and port in tools > preferences > network tab > advanced button

- Others , do you use a firewall? Most often the problem is you don't have a properly configured firewall (not allowing xolox access or security level set too high) . Especially wXP users - do not use that POS XP firewall.

- Join chat? Some peers or ops may be able to help with your individual problem.