ftp cannot log in using new user account
I am running a linux box using Proftpd as my ftp server and Webmin as a GUI administration interface for the system. I created a new user account in Webmin for a friend to set up a web site on the server, but he can not log in to the server with this new account. I have created users before using Webmin and they have all had no problems using FTP on the server. I have tested this account and can log on to the shell fine, but when I try to ftp using the account, I get a logon denied error. Where should I start looking to troubleshoot this?