When I select a server from the IRC Servers list I can successfully connect to it, However, when I add a new server to that list and then try to connect to it the connection fails. The IRC site does acknowledge the request to connect but does not complete the connection process. When I try to access the channel listings, for example, it reports back "Not On Line". This occurs only on the IRC server that I manually entered in the IRC Server list and not on the others that are already on that list. This started a few days ago but prior to that time it had worked properly. I've exhausted all of my ideas to no avail.

Why not post the error message?

There is no error message. The problem is that I try to join any channel on the site there is no response whatsoever from the site. I never get an acknowledgement that I'm connected to the site and when I try to communicate with the site it fails (for instance, when I try to identify myself to maintain my registered nick). Trying to get a channel listing fails and it reports that I'm "Not On Line" (the only error message I've ever gotten). For some unknown reason I'm apparently been knocked off line and I don't know how to get back on line or otherwise communicate with that site.

What is so weird about this is that this is the IRC server that I manually added to the list. I can go to any other IRC server listed without any problem. Also, up to a couple of days ago, I was able to go to this site without any difficulty and had been doing so for literally years.

"Not On Line" is not an actual error message in mIRC. Please post the hostname you tried to connect to and ALL responses from the server when connecting.