c# - Dropdownlist problem -

i don't understand why can't ddl selected value..

asp code:

<table>     <tr>       <th> annee:</th>          <td>             <asp:dropdownlist id="ddlannee" runat="server" />          </td>     </tr>     <tr>       <th colspan="2">          <asp:button id="btnvalidate" runat="server" onclick="btnvalidate_click"                                      text="validate"  />        </th>     </tr> </table> 

code behind:

protected void page_load(object sender, eventargs e)         {             if (!ispostback)             {                 bindcontrols();             }         }          public void bindcontrols()         {             this.ddlannee.datasource = new bll.annee_manager().list(false, true, null);             this.ddlannee.datatextfield = "intitule_an";             this.ddlannee.datavaluefield = "id_an";             this.ddlannee.databind();         }          protected void btnvalidate_click(object sender, eventargs e)         {             int id_an = int.parse( this.ddlannee.selectedvalue);          }     } } 

so, when put break point @ page load , binding part, it's ok, ddl filled correctly , page show correctly ddl. when click on button, arrive in btnvalidate_click method ddl empy!

i suppose i've forgot something.. please me!

thanks..

do not remove ispostback, bindcontrol method should in !ispostback condition otherwise never going selected value. make sure of method not clearing ddlannee dropdown.