Retrieving Values From Dynamically Created CascadingDropDown

After a couple of days of banging my head agaist the wall I am about to give up. I believe that what i am trying to do should be achieveable and that I am most of the way there.

I am attempting to create a product configuration page. The product ID is passed to the page via a querystring. I then retrieve a list of options that can be configured for that product from a SQL database. For each option I create a dropdown list. Each of these dropdowns are linked via an AJAX CascadingDropDown Control. Once the user has selected an option in all dropdown lists I want to concatenate the values of each dropdowns selectedvalue into a single string and then query the SQL database for a corresponding Product ID and display that on the page.

So far I have managed to create the cascading dropdowns and display them on the page. This much is working. However, when I attempt to retrieve the selected values I am getting nothing, Literally. Though the controls are on the page i cannot find them in the panel which I have placed them. I am fairly sure this is to do with losing the value on postback, but I am stumped as to how to fix it.

I would consider myself a beginner in the world of c# and .NET so any help would be much appreciated.

Below is the stripped out code to show where I am at the moment.

<asp:UpdatePanel ID="updItemDetails" runat="server"><ContentTemplate>
		Item No: <asp:Label ID="lblItemNo" runat="server">---</asp:Label></ContentTemplate><Triggers><asp:AsyncPostBackTrigger ControlID="cmdCalculate" EventName="click" /></Triggers>	</asp:UpdatePanel>                    <asp:Panel ID="phOptions" runat="server"></asp:Panel>			<asp:Button ID="cmdCalculate" runat="server"  Text="Calculate" OnClick="cmdCalculate_Click" />   

 protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {            
            int NodeID = Convert.ToInt32(Request.QueryString["NodeID"]);
            if (NodeID != null)
            {
                PageInfoByNode(NodeID);
            }
        }        
    }

    protected void PageInfoByNode(Int32 NodeID)
    {
        //Get Item Info From Shop
        string sql = "Select ConfigItem From Table1 Where Node=@NodeID";

        SqlConnection conn = new SqlConnection(System.Web.Configuration.WebConfigurationManager.ConnectionStrings["Shop"].ConnectionString);
        SqlCommand cmd = new SqlCommand(sql, conn);
        cmd.CommandType = CommandType.Text;
        cmd.Parameters.Add("@NodeID", SqlDbType.Int);
        cmd.Parameters["@NodeID"].Value = NodeID;

        conn.Open();
        SqlDataReader dr = cmd.ExecuteReader();
        while (dr.Read())
        {
            //Add Product Options
            AddOptions(dr["ConfigItem"].ToString());            
        }
        dr.Close();
        conn.Close();
    }

    protected void AddOptions(string ConfigItem)
    {
        string sql = "SELECT  ConfigID, Configurable FROM Table2 WHERE ConfigItem = @ConfigItem)";
        SqlConnection connParent = new SqlConnection(System.Web.Configuration.WebConfigurationManager.ConnectionStrings["Shop"].ConnectionString);
        SqlCommand cmdParent = new SqlCommand(sql, connParent);
        cmdParent.CommandType = CommandType.Text;
        cmdParent.Parameters.Add("@ConfigItem", SqlDbType.Char, 20);
        cmdParent.Parameters["@ConfigItem"].Value = ConfigItem;

        SqlDataAdapter adapter = new SqlDataAdapter(cmdParent);
        DataTable dt = new DataTable();
        adapter.Fill(dt);
        
        int i = 0;
        foreach (DataRow row in dt.Rows)
        {
            i++;
            //Create Dropdown List
            DropDownList ddl = new DropDownList();                        
            ddl.ID = "ddl" + i;

            //Create Dropdown Extender
            CascadingDropDown ddlE = new CascadingDropDown();
            ddlE.ID = "ddlE" + i;
            ddlE.TargetControlID = ddl.ID;

            ddlE.Category = row["ConfigID"].ToString();
            ddlE.PromptText = row["Configurable"].ToString();
            ddlE.ServicePath = "/ConifgOptions.asmx";
            ddlE.ServiceMethod = "GetOptions";
            //Set Parent Dropdown for all child items
            if (i > 1)
            { ddlE.ParentControlID = "ddl" + (i - 1).ToString(); }
            //Add Controls to panel
            phOptions.Controls.Add(ddl);
            phOptions.Controls.Add(ddlE);
        }
    }

    protected void cmdCalculate_Click(object sender, EventArgs e)
    {
        string orderingNumber;
        foreach (Control c in phOptions.Controls)
        {
            if (c is DropDownList)
            {
                DropDownList pcddl = (DropDownList)c;
                orderingNumber += pcddl.SelectedItem.Value;
            }
        }
        lblItemNo.Text = orderingNumber;        
    }