If you see the following error trying to do Active Directory LDAP queries using a secure connection (AuthenticationTypes.Secure): Type : System.Runtime.InteropServices.COMException, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 Message : The server is not operational. Source : System.DirectoryServices ErrorCode : -2147016646 …