how to get html genericconntrol value in code behind

[jaseem0712]

in my page i have a code like this"

<td>
    <span>Sex:&nbsp;</span>
   </td>
    <td>
   <span id="Sex_PDLabel" runat="server"></span>
 
  </td>

while running the page i am getting some value here..i want to save that value in my sql server database..so i want to take that value in my code behind page..i tried code something like this

Dim div As HtmlGenericControl = CType(FindControl("Sex_PDLabel"), HtmlGenericControl)
  Dim s As String = div.InnerText

but i am getting empty string.what is wrong with my code?? how i can find out the corresponding span id value in my code behind..
Thanks in advance