FTP Connections to an IIS FTP server using FTPS

Greetings,

I have an IIS7.5 server that has FTP configured for FTPS (http://www.iis.net/learn/publish/using-the-ftp-service/using-ftp-over-ssl-in-iis-7). I have set the FTP configuration to require SSL, and I've created and applied a self-signed certificate.

When I attempt to connect to that FTP server with CFFTP, using the existing username/password and also setting secure="true", I receive the following response:

"51 User Authentication Failed"

If I do not require SSL -- i.e. use FTP instead of FTPS -- this user successfully connects. 

When I try to use an ftp client such as CoreFTP, and configure it per these instructions (http://blogs.msdn.com/b/robert_mcmurray/archive/2009/05/01/ftp-clients-part-6-core-ftp-le.aspx), I get the following:

Connect socket #1048 to XX.YY.ZZ, port 21...

220 Microsoft FTP Service 

AUTH TLS 

234 AUTH command ok. Expecting TLS Negotiation. 

And then it hangs till it times out.

Any idea what I'm missing?

Thanks in advance.