Error: Sorry that username is already taken, please choose another one.

proc znc:request { nick host handle chan text } {
	global scriptCommandPrefix zncPasswordSecurityLevel zncPasswordLength zncnetworkname zncrealname zncquitmsg zncvhost zncDefaultUserModules zncDefaultNetworkModules usePreconfiguredNetworks bannednetworks
	set username [lindex $text 0]
	set email [lindex $text 1]
	set networkname [lindex $text 2]
	set server [lindex $text 3]
	set port [lindex $text 4]
	if {[regexp -nocase {^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}$} $email]} { 
                putserv "PRIVMSG $chan :The e-mail is invalid."
		return
	}
        if {[string tolower $networkname] in $bannednetworks} {
		putserv "PRIVMSG $chan :The network \002$networkname\002 is 7BANNED1."
		return
	} else {
		set password [znc:helpfunction:generatePassword  $zncPasswordSecurityLevel $zncPasswordLength ]
		if [ adduser $username ] {
			setuser $username COMMENT $email
			chattr $username +ZC
			znc:controlpanel:AddUser $username $password
                        znc:controlpanel:Set realname $username $zncrealname
                        znc:controlpanel:Set quitmsg $username $zncquitmsg
                        znc:controlpanel:Set bindhost $username $zncvhost 
			znc:blockuser:block $username
			znc:helpfunction:loadModuleList $username $zncDefaultUserModules
			if { $networkname != ""} {
				set preServer ""
				if { $usePreconfiguredNetworks } {
					set preServer [array names knownNetworks -exact [string tolower $networkname]]
				}
				znc:controlpanel:AddNetwork $username $networkname
				znc:helpfunction:loadNetModuleList $username $networkname $zncDefaultNetworkModules
				if { $preServer != "" } {
					foreach {networkname networkserver} [array get knownNetworks [string tolower $networkname]] {
						znc:controlpanel:AddServer $username $networkname $networkserver 
					}
				} else {
					if { $port != "" } {
						znc:controlpanel:AddServer $username $networkname "$server $port"
					}
				}
			}
                           puthelp "privmsg $chan :\002Success!\002 Your new ZNC \002\(\002with ident $username\002\)\002 will now be handled by a staff member. If your request is accepted, our bot will e-mail you with your new ZNC details and with login information."
                           puthelp "privmsg $chan :\002Syntax\002: !check $username for the status of your request."
		} else {
			puthelp "privmsg $chan :\0024Error1\002: Sorry \002$username\002 that username is already taken, please choose another one."
		}
	}
}