How to set the owner of an existing SQL Server database

I am trying to set the owner of a SQL Server database using C # and SMO. If the database does not exist, I can assign an owner. But if I want to set the owner of an existing database, I get an error.

Working code for new database:

Server server = new Server("WINSERVER\\SQLEXPR");
server.ConnectionContext.LoginSecure = true;
Database database = new Database(server, "MyDatabase");
db.Create();

database.SetOwner("SOMEOWNER", true)
database.Refresh();

      

        
        
        
      

    

Code doesn't work for existing database:

Server server = new Server("WINSERVER\\SQLEXPR");
server.ConnectionContext.LoginSecure = true;
Database database = new Database(server, "MyDatabase");

database.SetOwner("SOMEOWNER", true)
database.Refresh();

      

        
        
        
      

    

Mistake:

Microsoft.SqlServer.Management.Smo.InvalidSmoOperationException: You cannot perform this operation because the object was not created by benn.