关于oracle的小疑点求指教

关于oracle的小问题求指教
代码如下但是没有结果俺不执行只能执行到conn。open然后就跳到catch了求解求指教，先谢
 private void button1_Click(object sender, EventArgs e)
  {
  string str = "data source=sid;user=scott;password=tiger";
  OracleConnection conn = new OracleConnection(str);
  try
  {
  conn.Open();
  OracleCommand com = conn.CreateCommand();
  com.CommandText = "select * from scott.emp";
  OracleDataReader dr = com.ExecuteReader();
  while (dr.Read())
  {
  this.textBox1.Text = dr.GetOracleString(0).ToString();
  }
  dr.Close();
  }
  catch
  {
  MessageBox.Show("error");
  }
  finally
  {
  conn.Close();
  }

[解决办法]
string str = "data source=sid;user=scott;password=tiger";
连接字符串有问题
[解决办法]
http://wenku.baidu.com/view/48289b16866fb84ae45c8d5b.html 参考下别人怎么写的