Hope you don't mind some questions from an interop newbie ('m not even sure
what questions to ask, but I want to learn) ...

I'm trying to access a COM object (the MS Agent server) in VB.Net 2005.  I
can create the object that represents the server, access its methods and
properties, and more.  So far so good.

But at one point I need to obtain a reference to an interface the server
object supports, then call a method on that interface.  Here's some sample
code that some VB6 MS Agent folks think should work:

----------
dim AgentEx as IAgentEx

(code that creates and initializes AgentEx)
Dim ps As IAgentPropertySheet

ps = AgentEx ' this object should support the IAgentPropertySheet interface

(or)

ps = CType(objServer, IAgentPropertySheet)

----------

Both my attempts to assign a valueto ps fail with
System.InvalidCastException.

One oddity is that the code that initializes AgentEx uses a similar
technique:

Dim objServer = new AgentServer

Dim objAgentEx = objServer

And that works.  It's just the attempt to gain access to the
IAgentPropertySheet that fails.

Any ideas or suggestions?

Is there a way to query a COM object to find what Interfaces it supports (to
be sure IAgentPropertySheet is actually supposed to work)?

I don't know if this is a problem with my understanding of COM interop
(extremely limited to non-existent!).  Or with MS Agent.