Very strange problem with SelectedIndexChanged

Hello,

 I'm stuck with a strange problem when doing an autopostback on a dropdownlist.

Here is the sistuation:

I have a control containing a dropdownlist:
 1 <asp:DropDownList
2 ID="ddlSales"
3 runat="server"
4 AutoPostBack="True"
5 OnSelectedIndexChanged="ddlSales_SelectedIndexChanged">
6 </asp:DropDownList>

On the page behind, I have the following code:1 Protected Sub ddlSales_SelectedIndexChanged( Go to the complete details ...