DropDownList selectedindex = -1 after postback

Hi Experts,

The dropdownlist (DDL1) on my aspx page gets populated on page load just fine. On page load I set the selectedindex to 1.

I have Autopostback set to false on the dropdownlist.

When I click on a button, and go to the function behind that button click Updatebtn_Click(), I want to retrieve the selected item in DDL1. However, at this point I get an object reference error and DDL1.selectedindex = -1.

Could you tell me what's going on and how I can get the selected value without a flash on the page?

Here's the aspx:
Dropdownlist:
<asp:DropDownList AutoPostBack="false" ID="DDL1" runat="server" Font-Size="X-Small" width="120"></asp:DropDownList>

Button:
<asp:Button ID="Updatebtn" runat="server" Text="Update" Font-Size="1.0em" OnClick="Updatebtn_Click" />

The page has enableviewstate set to false.


Here's the code behind:

protected void Page_Load(object sender, EventArgs e)
    {

        if (!Page.IsPostBack && !Page.IsCallback)
        {

            InitAlertsPanel();

            DataTable dt = (DataTable)Session["dataTable"];
            grid1.DataSource = dt;
            grid1.KeyFieldName = "RowNumber";
            grid1.DataBind();


            // Register trigger for update panel
            ScriptManager1.RegisterAsyncPostBackControl(Button1);
            AsyncPostBackTrigger trigger = new AsyncPostBackTrigger();
            trigger.EventName = "Click";

            if (Button1.UniqueID.EndsWith(trigger.ControlID))
            {
                trigger.ControlID = Button1.UniqueID.ToString();
            }

        }
        else
        {
            //Bind the grid on every request
            BuildGrid1();


        }

        if (!IsPostBack){
            GetUPendingStatus(); // This populates DDL1

        }

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