title: DropDownList OnSelectedIndexChanged is not Firing
body: <p>My main purpose, populating the ddlCity DropDownList according to the ddlMedicalName selection. But my main problem is, although I try almost every solution to that problem, I couldnt make it firing ddlMedicalName_OnSelectedIndexChanged .</p>
  
  <p>I know, there is plenty of questions and answers about that problem, I have tried almos every one of them but still it doesn't work. I have read that EnableStateView=True should be applied not only to DropDownList but also to the whole page, So I have added the following code to the Web.Config:</p>
  
  <pre><code> &lt;system.web&gt;
  &lt;pages styleSheetTheme="MainTheme" enableViewState="true"/&gt;
  </code></pre>
  
  <p>And here is my code behind:</p>
  
  <pre><code>using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Web;
  using System.Web.UI;
  using System.Web.UI.WebControls;
  using System.Data.SqlClient;
  using System.Data;
  using System.Configuration;
  
  
  
  namespace MedicalBootStrap
  {
  
  public partial class WebForm1 : System.Web.UI.Page
  {
      Entity.medicaldbEntities context = new Entity.medicaldbEntities();
  
      protected void Page_Load(object sender, EventArgs e)
      {
  
          if (!Page.IsPostBack)
          {
              ddlBind();
          }
  
      }
  
      protected void ddlBind()
      {
  
          var orders = from order in context.Medicals
  
                       select new { order.MedicalID, order.medicalName, order.CityFK };
  
          var lstsrc = orders.ToList();
  
          ddlMedicalName.DataSource = lstsrc;
          ddlMedicalName.DataTextField = "medicalname";
          ddlMedicalName.DataValueField = "cityfk";
  
          ddlMedicalName.DataBind();
  
      }
  
      protected void ddlMedicalName_OnSelectedIndexChanged(object sender, EventArgs e)
      {
  
            int slc = Convert.ToInt32(ddlMedicalName.SelectedItem.Value);
  
          var orders = from order in context.Cities
                       where order.CityID == slc
                       select new { order.CityID, order.CityName};
  
          var lstsrc = orders.ToList();
  
          ddlMedicalName.DataSource = lstsrc;
          ddlMedicalName.DataTextField = "medicalname";
          ddlMedicalName.DataValueField = "cityfk";
  
          ddlMedicalName.DataBind();
      }
  
      protected void ddlRegion_SelectedIndexChanged(object sender, EventArgs e)
      {
  
      }
  
      protected void ddlCity_SelectedIndexChanged(object sender, EventArgs e)
      {
  
      }
  
      protected void SearchButton_Click(object sender, EventArgs e)
      {
  
      }   
   }
  }
  </code></pre>
  
  <p>And here is aspx:</p>
  
  <pre><code>&lt;%@ Page Title="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="MedizinischeLeistungen.aspx.cs" Inherits="MedicalBootStrap.WebForm1" EnableViewState="true" %&gt;
  &lt;asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server"&gt;
  &lt;/asp:Content&gt;
  &lt;asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server" EnableViewState="true"&gt;
  &lt;table id="SearchTable"&gt;
  &lt;tr&gt;
  &lt;td&gt;Medizinische Leistung&lt;/td&gt;
  &lt;td&gt;Region&lt;/td&gt;
  &lt;td&gt;Stadt&lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr id="SearchDropDown"&gt;
  
  &lt;td&gt;
      &lt;asp:DropDownList ID="ddlMedicalName" runat="server" EnableViewState="true" 
          AutoPostBack="True"  AppendDataBoundItems="true"
      OnSelectedIndexChanged="ddlMedicalName_OnSelectedIndexChanged"&gt;
      &lt;asp:ListItem Value="" Selected="True"&gt; - Product - &lt;/asp:ListItem&gt;
      &lt;/asp:DropDownList&gt;
  &lt;/td&gt;
  
  &lt;td&gt;
      &lt;asp:DropDownList ID="ddlRegion" runat="server" AutoPostBack="true" EnableViewState="true"
  onselectedindexchanged="ddlRegion_SelectedIndexChanged"&gt;
  &lt;asp:ListItem Value="" Selected="True"&gt; - Product - &lt;/asp:ListItem&gt;
      &lt;/asp:DropDownList&gt;
  &lt;/td&gt;
  &lt;td&gt;
      &lt;asp:DropDownList ID="ddlCity" runat="server" AutoPostBack="true" EnableViewState="true"
  onselectedindexchanged="ddlCity_SelectedIndexChanged"&gt;
  &lt;asp:ListItem Value="" Selected="True"&gt; - Product - &lt;/asp:ListItem&gt;
      &lt;/asp:DropDownList&gt;
  &lt;/td&gt;
  &lt;td&gt;
      &lt;asp:Button ID="SearchButton" runat="server" Text="Suche" onclick="SearchButton_Click" /&gt;
  
  &lt;/td&gt;
  &lt;/tr&gt;
  &lt;/table&gt;
  
  
  
  
  &lt;/asp:Content&gt;
  </code></pre>
  
  <p>Any help would be appreciated</p>