How to cast TableOwner in async mode?

So 2 have two models in 2 different modes: syn and asyn

 model = pfcSession.GetCurrentSession().GetCurrentModel();

 connection = pfcAsyncConnection.AsyncConnection_Connect(null, null, null, 20);
 model = connection.GetSession().GetCurrentModel();

I have checked and both models are valid and I have no issue casting the TableOwner tableowner from the two models. However, I cannot get a list of tables with async mode

TableOwner tableOwner = (TableOwner)model;
 if(tableOwner!=null)
 {
 tableOwner.ListTables().getarraysize();
 }

tableOwner is not null but ListTables() actually returns null error. I am not sure if I do not cast it properly or I need something special to make it work.