🚀 go-pugleaf

Hi, everyone
Just want to know if there is anybody successfully Indy.Sockets.Security.Tls.ServerIOHandlerTls for server-side autherntication and how to set properties for options. 
I created three files:
cert.pem, root.pem and key.pem
and snippet:
Indy.Sockets.Security.Tls.ServerIOHandlerTls tls =  new Indy.Sockets.Security.Tls.ServerIOHandlerTls();
tls.Options.LoadPrivateKeyFromFile("c:\\certificate\\key.pem","password");
tls.Options.LoadPublicCertificateFromFile("c:\\certificate\\cert.pem");
I also hook up tls with httpserver by this:
httpserver.IOHandler = (Indy.Sockets.ServerIOHandler)tls;
I got error:
System.Security.Cryptography.CryptographicException: Invalid data and/or password
   at Mono.Security.Authenticode.PrivateKey..ctor(Byte[] data, String password)
   at Mono.Security.Authenticode.PrivateKey.CreateFromFile(String filename, String password)
   at Indy.Sockets.Security.Tls.TlsServerOptions.LoadPrivateKeyFromFile(String AFileName, String APassword)
I don't know what is wrong. 
Any advice will be very helpful.
Liying