title: DropDownList RequiredFieldValidator is not working
body: <p>I have a DropDownList in my asp.net web page.
  The RequiredFieldValidator is not working. Thanks for looking at my code.</p>
  
  <pre><code>&lt;asp:DropDownList ID="Organization" runat="server"
      DataSourceID="OrganizationList"
      DataTextField="OrgName" DataValueField="OrgCode" CausesValidation="True"&gt;
  &lt;/asp:DropDownList&gt;
  
  &lt;asp:SqlDataSource ID="OrganizationList" runat="server"
      ConnectionString="&lt;%$ ConnectionStrings:MembershipDB %&gt;"
      SelectCommand="Admin_GetOrganizationDropDown" 
      SelectCommandType="StoredProcedure"&gt;&lt;/asp:SqlDataSource&gt;
  
  &lt;asp:RequiredFieldValidator runat="server" ID="RequiredFieldValidatorOrg"
      ControlToValidate="Organization"
      ErrorMessage="Organization is required." 
      Display="Dynamic" /&gt;
  </code></pre>