rowCount don`t count

Hi, i have a function, but my rowCount don´t count.

db = Ti.Database.open('laBD');
 
 if (NRow!=null){
        rows = db.execute('SELECT * FROM Home WHERE Home.Serie = ?',NRow);
        NRegistros=rows.rowCount;
 
 
        if (NRegistros!=0){
 
            db.execute('DELETE FROM Home WHERE Home.Serie = ?',NRow);
 
        }
    }

Why???

Thanks