SelectedIndexChanged event handler getting old index

<div style="margin: 0px; padding: 0px 1em 0px 0px;">
    <span style="margin: 0px; padding: 0px; vertical-align: top;">Route:</span>
    <asp:DropDownList id="Select1" runat="server" onselectedindexchanged="index_changed" AutoPostBack="true">
    </asp:DropDownList>
    <asp:Literal ID="Literal1" runat="server"></asp:Literal>
</div>

protected void index_changed(object sender, EventArgs e)
{
    decimal d = Convert.ToDecimal( Select1.SelectedValue );
    Literal1.Text = d.ToString();
}

if (!IsCallback && !IsPostBack)
        {
            // Do your page setup here
        }

if(!IsPostback) d.SelectedValue = "Default"