C#与Oracle链接的问题

private void Form1_Load(object sender, EventArgs e)
        {
            OracleConnection conn = new OracleConnection();
            conn.ConnectionString = "server=127.0.0.1;data source=ASJZ;user id=as;password=jiazhen;";
            OracleDataAdapter da = new OracleDataAdapter("select * from ASH", conn);
            DataSet ds = new DataSet();
            da.Fill(ds, "ASH");
            dataGridView1.DataSource = ds.Tables["ASH"];
        }

这个程序运行时，提示vshost.exe已停止工作。请问这个问题该如何解决。谢谢。