MT-threading in the example of chem4

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_Geant4 Version:_11.2

Dear friends,

When I used the multithreaded mode of chem4, I noticed the message about how to set it in chem4.cc,

// Construct the run manager according to whether MT is activated or not
  //
  auto* runManager= G4RunManagerFactory::CreateRunManager();

  if((commandLine = parser->GetCommandIfActive("-mt")))
  {
    int nThreads = 2;
    if(commandLine->GetOption() == "NMAX")
    {
      nThreads = G4Threading::G4GetNumberOfCores();
    }
    else
    {
      nThreads = G4UIcommand::ConvertToInt(commandLine->GetOption());
    }

    runManager->SetNumberOfThreads(nThreads);
  }

  G4cout << "**************************************************************"
         << "******\n===== Chem4 is started with "
         << runManager->GetNumberOfThreads() << " of "
         << G4Threading::G4GetNumberOfCores()
         << " available threads =====\n\n*************************************"
         <<"*******************************"
         << G4endl;

So I used "./chem4 -mt 8 ". But the print information is

===== Chem4 is started with 0 of 12 available threads =====.

This means that multithreading is not running, why is this?

Thank you
Best wishes.