VS 2010 [RESOLVED] NullReferenceException and I don't know why.

Private _listOfItems As List(Of Item)
 
    ''' <summary>
    ''' This will check for ItemAttachments and then add the item to a list.
    ''' </summary>
    ''' <param name="item">Item to check for attachments</param>
    ''' <remarks></remarks>
    Private Sub CheckForItemAttachments(ByVal item As Item)
        If item.HasAttachments Then
            _listOfItems.Add(item)' Errors right here with A first chance exception of type 'System.NullReferenceException' occurred in ISSvc2.exe
 
        End If
    End Sub