DropDownList do not run the code behind
<p>hy,
i configured <code>dropdownlist</code>:</p>

<pre><code>&lt;asp:DropDownList ID="ddl_filter1" runat="server" Width="120px" DataSourceID="ObjectDataSource1"
                                        DataTextField="PLC" DataValueField="PLC" OnSelectedIndexChanged="ddl_filter1_SelectedIndexChanged" /&gt;
</code></pre>

<p>and i want that when i choose a value from the <code>DropDownList</code> an event will happen</p>

<p>but for somereason the code behind do not run.</p>

<p>what is the problem in my code ?</p>
