There's a bug causing this, which we weren't aware of until now. The bug is in the method SSLFTPCertificate.ShowCertificateManager(), which is called in the example. Because of this, you're not going to be able to run these examples in the example viewer. Instead, I suggest that you make your own Visual Studio project and copy the code in the C# Code tab into it. It should work as-is, except for the PrintLine() and PrintLines() methods, which you can replaced with calls to Console.WriteLine(). You'll also need to add the following Using statement:
using EnterpriseDT.Net.Ftp;