How to create a Custom Contacts Folder in VSTO?

I'm trying to create an empty Contacts folder in Outlook 2007 addin using C# in Visual Studio 2010, but it seems like I can only create a folder in the InBox, is that true?

Below is my code:

    private void CreateContactsFolder()
    {
        Outlook.Folder allContacts = (Outlook.Folder)
            this.Application.ActiveExplorer().Session.GetDefaultFolder
            (Outlook.OlDefaultFolders.olFolderContacts);

        Outlook.MAPIFolder customFolder = null;
        string folderName = "All Contacts";

        customFolder = (Outlook.Folder)allContacts.Folders.
            Add(allContact开发者_如何学编程s, Outlook.OlDefaultFolders.olFolderContacts);
    }

You can create a folder under "Contacts" by specifying the type of folder you need.

Outlook.NameSpace outlookNameSpace = application.GetNamespace("MAPI");

Outlook.MAPIFolder contactsFolder =
                    outlookNameSpace.GetDefaultFolder(
                    Outlook.OlDefaultFolders.olFolderContacts);


MAPIFolder ContactsSubFolder = contactsFolder.Folders.Add("Contacts Sub Folder", Outlook.OlDefaultFolders.olFolderContacts);