change DropdownList Datasource Dynamicly
<p>I have a <code>dropDownlist</code> that have tow <code>Datasource</code> with names <code>Datasource1</code>,<code>Datasource2</code>. 
when the page_Load accrued the datasource1 is assigned to <code>Dropdownlist</code>. I have a button on page that i want when i clicked on button, Datasource2 assign to <code>Dropdownlist</code> in <code>button click event</code> i wrote this:</p>

<pre><code>Ddl_Num.DataSource = SqlDataSource8;
      Ddl_Num.DataBind();
</code></pre>

<p>but it doesn't changed.
how can i do that?</p>
