DropDownList.SelectedValue not taking effect

Question

This may seem like a duplicate question but I don't think it is. I'm setting up my asp:DropDownList in the ASPX page and setting it's SelectedValue during the RowDataBound event after checking if the current gridview row is the being edited. No errors are thrown when I set the SelectedValue property of the control and when I check it immediately after setting it, it hasn't changed.

Here's the relevant code

            <asp:SqlDataSource
                ID="DataSourceAnswerGroups"
                runat="server"
                ConnectionString="<%$ ConnectionStrings %>"
                DataSourceMode="DataSet"
                SelectCommand="
                    SELECT
                        Id
                       ,Description
                    FROM dbo.table
                    WHERE Active = 1
                    ORDER BY Description
                    ;
                " />
            <asp:GridView
                ID="GridView"
                runat="server"
                OnRowDataBound="GridView_RowDataBound">
                <Columns>
                    <asp:TemplateField HeaderText="Answer Group" SortExpression="AnswerGroup" ItemStyle-Wrap="false" ItemStyle-CssClass="left">
                        <ItemTemplate>
                            <%# Eval("AnswerGroup") %>
                        </ItemTemplate>
                        <EditItemTemplate>
                            <asp:DropDownList
                                ID="ddlAnswerGroupEdit"
                                runat="server"
                                DataSourceID="DataSourceAnswerGroups"
                                DataValueField="Id"
                                DataTextField="Description"/>
                        </EditItemTemplate>
                    </asp:TemplateField>
                </Columns>
            </asp:GridView>

Code behind

    protected void GridView_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow && e.Row.RowIndex == GridView.EditIndex)
        {
            DropDownList ddlAnswerGroupEdit = (DropDownList)e.Row.FindControl("ddlAnswerGroupEdit");
            ddlAnswerGroupEdit.SelectedValue = GridView.DataKeys[e.Row.RowIndex].Values["AnswerGroupId"].ToString();
            Response.Write(GridView.DataKeys[e.Row.RowIndex].Values["AnswerGroupId"].ToString() + "<br/>"); // this outputs the correct guid
            Response.Write(ddlAnswerGroupEdit.SelectedValue + "<br/>"); // this always outputs the same guid, the one that represents the first item on the list.
        }
    }

There are no other manipulations of the DdataSource or the DropDownList anywhere in the code. The default selection should be changing but it is silently failing. Any help would be appreciated.

Answer 1

Of all the stupid issues to have. This didn't fix it but it did get me going in the right direction. It was a case sensitivity issue. The SQL Server was returning the guiid in uppercase and the control items were in lowercase. This is the only fix I had to make:

ddlAnswerGroupEdit.SelectedValue = GridView.DataKeys[e.Row.RowIndex].Values["AnswerGroupId"].ToString().ToLower();