Win32_ComputerSystem can not retrieve VM list in Server 2012 R2

Below code use to work on Win2008 or 2012. Recently, I upgraded my system to WIn2012 R2, the ManagementObjectCollection will throw "invalid class" exception. Any clue to fix this?

ObjectQuery  query = new ObjectQuery("SELECT * FROM MsVM_ComputerSystem WHERE Caption LIKE 'Virtual%' ");
using (ManagementObjectSearcher searcher = new ManagementObjectSearcher(manScope, query))
                {
ManagementObjectCollection collection = searcher.Get();
if (collection != null)
{
 foreach (ManagementObject obj in collection)
 {