SQLite的“数据库已锁定”

我无法摆脱“数据库已锁定”错误。。。即使我使用互斥锁来控制对数据库访问的访问。

    void driver_Transaccion(object sender, AttendanceReader.MarcacionEventArgs e)
    {
        if (_transaccion != null)
        {
            try
            {
                using (GlobalMutex.GetMutex())
                {
                    using (var db = new DataWare.monitorEntities())
                    {
                          /* some instructions */
                          /* ..... */
                          db.SaveChanges(); /* A database lock occurs here */
                    }
                }
             }
             catch (Exception ex)
             {
                ErrorLog.Save(ex);
             }
        }
    }

public class GlobalMutex : IDisposable
{
    private Mutex _mutex;
    private bool _acquired;

    public GlobalMutex()
    {
        _mutex = new Mutex(false, "RELOJ_ELO_20181004");
        _acquired = _mutex.WaitOne();
    }

    public static IDisposable GetMutex()
    {
        return new GlobalMutex();
    }

    public void Dispose()
    {
        if (_acquired)
            _mutex.ReleaseMutex();
        _mutex.Dispose();
        _mutex = null;
    }
}

詹姆