title: selectedindexchanged event not firing
body: <p>i have three <code>dropdownlists</code> with <code>autopostaback=true</code>,but the problem is that for second <code>dropdownlist</code> only <code>pageload</code> is called but it's <code>selectedindexchanged</code> is not firing! what can i do?(<code>dropdownlists</code> are in <code>updatepanel</code> )</p>
  
  <pre><code>EDIT:
   protected void Page_Load(object sender, EventArgs e)
      {
          if (DDL_d1.Items.Count == 0)
          {
              SqlDataReader dr = null;
              DbAccessor db = new DbAccessor();
              dr = db.SqlSelectS("true", "SELECT Fname FROM [Tbl_Amoozesh]");
              DDL_d1.Items.Clear();
              while (dr.Read())
                  DDL_d1.Items.Add(dr[0].ToString());
              db.Dispose();
          }
      }
      protected void d1(object sender, EventArgs e)
      {
  
          DDL_d1.AutoPostBack = false;
          SqlDataReader dr = null;
          DbAccessor db = new DbAccessor();
          dr = db.SqlSelectS(DDL_d1.SelectedValue,"SELECT Fname FROM [Tbl_Amoozesh] where Fname = @a");
          DDL_d2.Items.Clear();
          DDL_d2.Items.Add(new ListItem("hi"));
          while (dr.Read())
              DDL_d2.Items.Add(dr[0].ToString());
          db.Dispose();
  
  
  
  
      }
      protected void d2(object sender, EventArgs e)
      {
  
          SqlDataReader dr = null;
          DbAccessor db = new DbAccessor();
          dr = db.SqlSelectS(DDL_d2.SelectedValue, "SELECT Lname FROM [Tbl_Amoozesh] where Fname = @a");
          DDL_d3.Items.Clear();
          while (dr.Read())
              DDL_d3.Items.Add(dr[0].ToString());
          db.Dispose();
  
      }
  </code></pre>