Proftpd worked before I re-installed ISPConfig.
All I did was uninstall ISPConfig then reboot the server, then install ISPConfig with the same setup I had before. I chose the complete uninstall option. I used expert mode to use suexec for cgi as per the documentation.
ISPConfig worked before with proftpd then I reinstalled and everything works except proftpd.
Thanks for all your help.