Do you have sufficient permissions for accessing that mailbox and its
Calendar folder?

I did a quickie console app using C# and VS2005, Framework 2.0 running on
Outlook 2007.

I hard coded the mailbox recipient and since that Outlook setup has multiple
profiles I had to select an Exchange profile on startup. Other than that it
ran seamlessly and without errors and displayed one at a time all the
appointments.

I created 1 recurring appointment in my sales mailbox, but the principle
should apply even if the folder has many different appointments, mixing
recurring and non-recurring.

The Outlook profile used was my dog's profile against his mailbox on my
Exchange server, so Outlook was logged in as my dog. That profile was able
to access my sales mailbox, but my dog has permissions on that mailbox (he's
my sales manager).

Here's the code I used (appropriate references were set of course):

using System;
using System.Collections.Generic;
using System.Text;
using Outlook = Microsoft.Office.Interop.Outlook;
using System.Windows.Forms;

namespace ConsoleApplication1
{
   public partial class Program
   {
       static void Main(string[] args)
       {
           bool Foobar = false;
           Foobar = GetAppointments();
       }

    private static bool GetAppointments()
    {

       Outlook.Application oApp = new Outlook.Application();
       Outlook.NameSpace oNS = oApp.GetNamespace("MAPI");
       Outlook.AppointmentItem oAppt = null;
       int intFoo = 0;

       //create recipient
       Outlook.Recipient oRcp =
oNS.CreateRecipient("sales@slovaktech.com");

       //Get calendar info (appointments)
       Outlook.MAPIFolder oFdr = oNS.GetSharedDefaultFolder(oRcp,
Outlook.OlDefaultFolders.olFolderCalendar);
       if (oFdr != null)
       {
           Outlook.Items oItms = (Outlook.Items)oFdr.Items;
           oItms.IncludeRecurrences = true;

           string strFilter = "([End] > \'September 1, 2006 12:00 AM\' AND
[Start] <= \'March 1, 2007 12:00 AM\')";

           Outlook.Items oApps = oItms.Restrict(strFilter);
           oApps.Sort("[Start]", false);
           oApps.IncludeRecurrences = true; //blnIncludeRecurrences;

           try
           {
               oAppt = (Outlook.AppointmentItem)oApps.GetFirst();
               intFoo = (int)oAppt.Class;
           }
           catch
           {
               intFoo = 0;
           }

           if (intFoo == 26)
           {
               while (oAppt != null)
               {
                   System.Windows.Forms.MessageBox.Show("Subject = " +
oAppt.Subject + " Start = " +
                       oAppt.Start.ToString("MMM dd, yyyy HH:mm"));

                   oAppt = (Outlook.AppointmentItem)oApps.GetNext();
               }
               return true;
           }
           else
           {
               return false;
           }
       }
       else
       {
           return false;
       }
   }
 }
}