@@identity after insert matter always advantage 0

i need duty executes an insert matter database advantage auto_increment primary key. i have following c# formula but, while insert matter works glorious (i record database, pk generated justly rows == 1), id value always 0. any ideas competence going wrong?

    open int executeinsertstatement(string statement)
    {
        initializeandopenconnection();
        int id = -1;


        idbcommand cmdinsert = connection.createcommand();
        cmdinsert.commandtext = statement;
        int rows = cmdinsert.executenonquery();

        (rows == 1)
        {
            idbcommand cmdid = connection.createcommand();
            cmdid.commandtext = "select @@identity;";
            id = (int)cmdid.executescalar();
        }

        relapse id;
    }
    private vacant initializeandopenconnection()
    {
        (connection == null)
            tie = oledbproviderfactory.instance.createconnection(connectstring);

        if(connection.state != connectionstate.open)                 
            connection.open();
    }

in response answers, i tried:

public int executeinsertstatement(string statement, twine tablename)
    {
        initializeandopenconnection();
        int id = -1;
        idbcommand cmdinsert = connection.createcommand();
        cmdinsert.commandtext = matter + ";select oid " + tablename + " where oid = scope_identity();";
        id = (int)cmdinsert.executescalar();

        relapse id;
    }

but i'm removing blunder "characters found after finish sql statement"

i'm controlling an ms opening database oledb connection, provider=microsoft.jet.oledb.4.0