Can you give me a hand with using CDO, CDOEXM in C#?

Hello,

please take a look at the following code:
======================================
CDO.PersonClass prsmbx = new CDO.PersonClass ();
string strLDAP;
strLDAP = "LDAP://...";
prsmbx.FirstName = NTUser;
prsmbx.Fields ["userAccountControl"].Value = 0x0200;
prsmbx.Fields.Update ();
prsmbx.DataSource.SaveTo _
(strLDAP, null, 0, 0, 0, "Administrator", "pass");

CDOEXM.IMailboxStore mbx = (CDOEXM.IMailboxStore)prsmbx.GetInterface ("IMailboxStore");
mbx.CreateMailbox ("LDAP://...");
prsmbx.Email = "SMTP:" + NTUser + "@domain.org";
prsmbx.Fields ["mailnickname"].Value = "HELLO";
prsmbx.Fields.Update ();
prsmbx.DataSource.Save ();
=========================================

I don't know what's wrong, I catch an Exception say that "An unexpected error occurred".

I just wana add a user with exchange mailbox enabled in C# code,
do you know how to do this?

Miller regrads