Either you are typing the password incorrectly (chicken isnt the same as ChIcKeN or CHICKEN, passwords are case sensitive) or someone else has that nick registered. DALnet does have an option to have your password sent to you thru SENDPASS, /nickserv sendpass nick email address (like /nickserv sendpass persian the-email-you-registered-with)
The email address that you specify in that command must match the email address they have on file for the nickname in question. The SENDPASS command will also be disabled if your MAILBLOCK option has been turned on.
You could try checking to see if someone else has the nick registered by seeing if the hostmask matches your own. (remember that you have to identify to a nick within each 30 day period or its dropped and someone else can register it) In any mIRC window, type /whois samas (whatever nick you are using), you will see a line like samas is something@something.something.else. then type /nickserv info persian and compare
