title: Asp.Net Dropdownlist SelectedIndexChanged in update panel, even when <Triggers> used
body: <p>Can anyone tell me why is this not working? I have searched everywhere already.<br>
  Usually when I do this, it works without triggers.</p>
  
  <pre><code> &lt;asp:UpdatePanel ID="UpdatePanel1" runat="server"&gt;
              &lt;ContentTemplate&gt;
          &lt;div style="width:15%;float:left;"&gt;
  
              &lt;asp:Image ID="Image1" runat="server" ImageUrl="~/Img/Untitled1.png" CssClass="imagez" /&gt;
  
          &lt;/div&gt;
                  &lt;/ContentTemplate&gt;
              &lt;Triggers&gt;
                  &lt;asp:AsyncPostBackTrigger ControlID="DropDownList1" EventName="SelectedIndexChanged" /&gt;
              &lt;/Triggers&gt;
          &lt;/asp:UpdatePanel&gt;
          &lt;div style="width:85%;float:left;height:100%;padding-top:2%;"&gt;
  
              &lt;asp:Label ID="Label2" runat="server" Text="CPU" CssClass="auto-style7" Font-Names="sans-serif"&gt;&lt;/asp:Label&gt;
              &lt;br /&gt;
  
              &lt;asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" CssClass="bla" DataSourceID="SqlDataSource1" DataTextField="Name" DataValueField="Name" Font-Names="sans-serif" EnableViewState="true" AppendDataBoundItems="true" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged"&gt;
                  &lt;asp:ListItem Selected="True"&gt;Pick a CPU&lt;/asp:ListItem&gt;
              &lt;/asp:DropDownList&gt;
  </code></pre>
  
  <p>This is the code for <code>SelectedIndexChanged</code>:</p>
  
  <pre><code>protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
  {
      Label2.Text = "please";
  }
  </code></pre>