POS For .NET：无法设置PosPrinter的属性属性

PosPrinter posPrinter = (PosPrinter)posExplorer.CreateInstance(posPrinterInfo);
posPrinter.Open();
posPrinter.Claim(1000);
posPrinter.DeviceEnabled = true;
posPrinter.PageModeVerticalPosition = 10; //<--- Exception thrown: Failed to set property PageModeVerticalPosition

    Microsoft.PointOfService.PosControlException was unhandled
    Message="Failed to set property PageModeVerticalPosition."
    Source="Microsoft.PointOfService"
    ErrorCodeExtended=0
    StackTrace:
           at Microsoft.PointOfService.Legacy.LegacyProxy.SetProperty(String propertyName, Object propertyValue)
           at Microsoft.PointOfService.Legacy.LegacyPosPrinter.set_PageModeVerticalPosition(Int32 value)
       ....