Proftpd won't start
There are several reason why proftpd might not start.
1) Make sure that it's installed.
You should be able to run
rpm -q proftpd
on RedHat and it should show you the current version. If it says that proftpd is not installed, then you must install it.
Watch for errors.
One common problem is another conflicting ftp daemon. Remove the other ftp daemon
rpm -e --nodeps other-ftp
and then run ./proftpd.sh again.
2) Ensure IP's are setup correctly
a) make sure that the server ip is setup with the hostname in the /etc/hosts file.
b) make sure that the server ip is *not* in the /etc/proftpd.vhosts.conf as a VirtualHost
Once you've got it setup and installed restart it by running:
service proftpd restart