C# – GridView RowUpdating does not get the new values

I have at the moment a problem with RowUpdating from a GridView and accessing the new values. I add a dynamic DataTable to my GridView.DataSource and bind to it. If I use the update button nothing happens and I get back to my normal GridView.
Here's my Page_Load event:

protected void Page_Load(object sender, EventArgs e)
{
    Control test = GetPostBackControl(Page);
    if (Page.IsPostBack)
    {
        if ((test.ID == "SumbitSearch") && (DropDownListFrom.Text != "") && (DropDownListTo.Text != "") && (SearchField.Text != ""))
        {
            DataTable result = new DataTable();
            string from = null;
            string to = null;

            switch (DropDownListFrom.SelectedIndex)
            {
                case 0:
                    from = DropDownListFrom.Items[0].Value;
                    break;
                case 1:
                    from = DropDownListFrom.Items[1].Value;
                    break;
                case 2:
                    from = DropDownListFrom.Items[2].Value;
                    break;
            }

            switch (DropDownListTo.SelectedIndex)
            {
                case 0:
                    to = DropDownListTo.Items[0].Value;
                    break;
                case 1:
                    to = DropDownListTo.Items[1].Value;
                    break;
                case 2:
                    to = DropDownListTo.Items[2].Value;
                    break;
            }

            result = LoadGridView(from, to);
            GridViewResult.DataSource = result;
            Session["Result"] = result;
            GridViewResult.DataBind();

            GridViewResult.Columns[0].Visible = true;
            GridViewResult.Columns[1].Visible = true;

            GridViewResult.HeaderRow.Cells[0].Width = Unit.Pixel(110);
            GridViewResult.HeaderRow.Cells[1].Width = Unit.Pixel(60);
            GridViewResult.HeaderRow.Cells[3].Text = "Nach: " + from;
            GridViewResult.HeaderRow.Cells[4].Text = "Von: " + to;
        }
    }
    else
    {
        GridViewResult.DataBind();
    }
}

Later, the GridView should only appear if both DropDownLists are used and the SearchField is not empty. I also check if the button which execute the PostBack is the search button.

Here is what I added to the RowUpdating EventHandler:

protected void TaskGridViewResult_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
    GridViewResult.DataSource = (DataTable)Session["Result"];
    for (int i = 0; i < GridViewResult.Columns.Count; i++)
    {
        DataControlFieldCell cell = GridViewResult.Rows[e.RowIndex].Cells[i] as DataControlFieldCell;
        GridViewResult.Columns[i].ExtractValuesFromCell(e.NewValues, cell, DataControlRowState.Edit, true);
    }

    GridViewResult.EditIndex = -1;
    DataBind();
}

What is going wrong?

Last Change: More Information (@jwiscarson)

I’m sorry, I was in hurry. I will try to give you a better view.
In that project, the users could select 2 categories, enter a search string and the result will show in a GridView. The RowUpdating stuff is for the "admin user".
Here is my problem, if the "admin user" click on edit, change the value of the cell and execute the update, the value would not changed in the DataTable.

Without seeing your markup, it's hard for […] based on some search
criteria?

I add GridViewResult as markup in my project.

I'm also not sure why […] within that button's Click event.

Yes, I thought that too! But I read in a blog it is better to put the code into Page_Load(), if you are working with GridViews. I believed him. Is it okay, to put that code into the click event handler from my button? I'm very new to that. I just could read lots of blogs, msdn and ask here.

TaskGridViewResult_RowUpdating is also added as markup to my code. Could I also create this and the GridView in my CreateChildControls()?

As markups I have two DropDownLists, a TextBox for the search string, a search submit Button and the GridView.

At the moment, i havent the exactly code here but the GridView looks like:

<asp:GridView ID="GridView1" runat="server"
    OnRowUpdating="TaskGridViewResult_RowUpdating">
    <!-- // More of that... -->
    <Columns>
        <asp:CommandField ShowEditButton="True" />
        <asp:CommandField ShowDeleteButton="True" />
    </Columns>
</asp:GridView>

I could give you more details tomorrow.

Maybe I forgot this. Before I could click the update button and execute the TaskGridViewResult_RowUpdating event to change the value of the cell. I set the row editable with:

 protected void TaskGridViewResult _RowEditing(object sender, GridViewEditEventArgs e)
  {
    GridViewResult.EditIndex = e.NewEditIndex;
    DataBind();
  }

Next Change:
I added to the GridView few TemplateFields like:

<asp:TemplateField HeaderText="test">
    <EditItemTemplate>
        <asp:TextBox ID="TextBox1" runat="server" Text='<%# Bind("from") %>'>   </asp:TextBox>
    </EditItemTemplate>
    <ItemTemplate>
        <asp:Label ID="Label2" runat="server" Text='<%# Bind("from") %>'></asp:Label>
    </ItemTemplate>
</asp:TemplateField>

This is it, I have access to the new value with:

string test = ((TextBox)row.FindControl("TextBox1")).Text;

in TaskGridViewResult_RowUpdating()

Now, I just have to bind the template dynamically with the values from the dropdown list, and that’s it I think.

Thanks!