There is one more step you may need to do. su as root and open up an editor. Open the file /etc/inetd.conf
Check the file for a line that contains:
#ftp stream tcp nowait root /usr/sbin/tcpd proftpd
If you don't see it, then just type it in. (I use tabs between the words.) Make sure you change the path from /usr/sbin/tcpd to whatever is correct for your system.
Delete the # at the beginning of the line
If you made a change, then restart your inetd server by typing in the command:
kill -HUP 'cat /var/run/inetd.pid'
Don't worry, that command will find the inetd process and restart it using the kill command.
Hope that helps!