Try another server address. Due to attacks that DALnet faced, and due to the fact that many attack bots are coded to point to the irc.dal.net address, DALnet closed off their main server pool. It does sometimes work I have found, but more often than not you will have problems with it.
You can get a list of DALnet servers here
, but I recommend serverpronto.dal.net for now.
Hope this works!