NullReference in PrintQueueCollection

Hi,
Exception:
System.Printing Object reference not set to an instance of an object.
    at MS.Internal.PrintWin32Thunk.EnumDataThunkObject.GetPrintSystemValuesPerPrintQueues(PrintServer printServer, EnumeratedPrintQueueTypes[] flags, Queue`1 printObjectsCollection, String[] propertyFilter)

   at System.Printing.PrintQueueCollection..ctor(PrintServer printServer, String[] propertyFilter, EnumeratedPrintQueueTypes[] enumerationFlag)
It occurs when invoking:
vat x = printServer.GetPrintQueues(new[] { EnumeratedPrintQueueTypes.Local, EnumeratedPrintQueueTypes.Connections });
Any ideas, what is the reason and how best to fix?