What could be the cause??

VB Code:

Set ocalItems = myNamespace.GetSharedDefaultFolder(myRecipient, Outlook.OlDefaultFolders.olFolderCalendar).Items
        
        Set Appointment = ocalItems.GetFirst
        
            Do While Not (Appointment Is Nothing)
                bla bla
 
            Set Appointment = ocalItems.GetNext
            Loop

What could be the cause that not all of the appointments are loaded?
When I loop the appointments, some doesn't show up.....