Edit command erroring out in gridiview
<p>Iam unable to identify the problem which is causing the edit command to fail</p>

<p>GridView Code</p>

<pre><code>&lt;asp:GridView ID="GridView1" runat="server" AllowPaging="True" 
    AllowSorting="True" AutoGenerateColumns="False" CellPadding="4" 
    DataKeyNames="Requestid" DataSourceID="SqlDataSource1" ForeColor="#333333" 
    GridLines="None" Height="321px" Width="604px"&gt;
    &lt;AlternatingRowStyle BackColor="White" /&gt;
    &lt;Columns&gt;
     &lt;asp:CommandField ShowEditButton="True"  UpdateText="Submit" /&gt;
        &lt;asp:BoundField DataField="Requestid" HeaderText="Requestid" ReadOnly="True" 
            SortExpression="Requestid" /&gt;
        &lt;asp:BoundField DataField="Receiveddate" HeaderText="Receiveddate" 
            SortExpression="Receiveddate" /&gt;
        &lt;asp:BoundField DataField="Ctname" HeaderText="Ctname" 
            SortExpression="Ctname" /&gt;
        &lt;asp:TemplateField HeaderText="Requestor" SortExpression="Requestor"&gt;
            &lt;EditItemTemplate&gt;
                &lt;asp:DropDownList ID="DropDownList1" runat="server" 
                    DataSourceID="SqlDataSource2" DataTextField="analystname" 
                    DataValueField="contact_id" SelectedValue='&lt;%# Bind("Requestor") %&gt;'&gt;
                &lt;/asp:DropDownList&gt;
                &lt;asp:SqlDataSource ID="SqlDataSource2" runat="server" 
                    ConnectionString="&lt;%$ ConnectionStrings:Customers %&gt;"         SelectCommand="SELECT [contact_id], [first_name]+ space(1)+ [last_name] as analystname FROM [contact]
order by contact_id"&gt;&lt;/asp:SqlDataSource&gt;
            &lt;/EditItemTemplate&gt;
            &lt;ItemTemplate&gt;
                &lt;asp:Label ID="Label1" runat="server" Text='&lt;%# Bind("Requestor") %&gt;'&gt;&lt;/asp:Label&gt;
            &lt;/ItemTemplate&gt;
        &lt;/asp:TemplateField&gt;
    &lt;/Columns&gt;
    &lt;EditRowStyle BackColor="#CC3300" /&gt;
    &lt;FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" /&gt;
    &lt;HeaderStyle BackColor="#CBB06D" Font-Bold="True" ForeColor="White" /&gt;
    &lt;PagerStyle BackColor="#2461BF" ForeColor="White" HorizontalAlign="Center" /&gt;
    &lt;RowStyle BackColor="#EFF3FB" /&gt;
    &lt;SelectedRowStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333" /&gt;
    &lt;SortedAscendingCellStyle BackColor="#F5F7FB" /&gt;
    &lt;SortedAscendingHeaderStyle BackColor="#6D95E1" /&gt;
    &lt;SortedDescendingCellStyle BackColor="#E9EBEF" /&gt;
    &lt;SortedDescendingHeaderStyle BackColor="#4870BE" /&gt;
&lt;/asp:GridView&gt;

&lt;asp:SqlDataSource ID="SqlDataSource1" runat="server" 
    ConnectionString="&lt;%$ ConnectionStrings:Customers %&gt;" SelectCommand="SELECT RR.Requestid,Convert(varchar(20),RR.Receiveddate,100) as Receiveddate,RR.Ctname,C.First_Name +Space(1) + C.Last_NAME as Requestor  from report_request_draft RR inner join Contact C on RR.requestor = C.contact_id
where clonedfromid is not null"

UpdateCommand="UPDATE [REPORT_REQUEST_DRAFT] SET  [REQUESTOR] = @Requestor  WHERE [requestid] = @requestid"&gt;

&lt;/asp:SqlDataSource&gt;
</code></pre>

<p>When i click on the edit command button it gives me the below error</p>

<p><strong>Error</strong></p>

<p>'DropDownList1' has a SelectedValue which is invalid because it does not exist in the list of items.
Parameter name: value 
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. </p>

<p>Exception Details: System.ArgumentOutOfRangeException: 'DropDownList1' has a SelectedValue which is invalid because it does not exist in the list of items.
Parameter name: value</p>
