Ch 9 #10 ... works fine in regular dropdowns but does not work when the two dropdowns are cascading ??? ...

"Could not find control <name of the first dropdown> in ControlParameter <name of the parameter>"

Am I missing something???

I found the answer to my problem:

Move the DataSource declaration inside of the DetailsView InsertTemplate field which has a DropDown that's referencing that DataSource's Id and it'll be able to find controls within the details view.

I am having the same problem. However, your solution works only if you only need that DataSource for just one control. If you need it for multiple controls that are in other containers then if you encapsulate it within one container then it will not be able to be seen by controls referencing it from other containers. I don't want to have redundant DataSources but I don't see a way around it. This is obviously a bug in the .NET Framework.

Hello,
Here is a solution : as Microsoft's ControlParameter cannot find bound control if it's in another container, I created my own parameter, overriding the "Evaluate" method.

using System;
using System.Collections.Generic;
using System.Text;
using System.Web.UI.WebControls;
using System.Web.UI;
using System.Reflection;
using System.Web;

namespace ...
{
    public class CrossContainerControlParameter : ControlParameter
    {
        /// <summary>
        /// Updates and returns the value of the <see cref="T:System.Web.UI.WebControls.ControlParameter "></see> object.
        /// </summary>
        /// <param name="context">The current <see cref="T:System.Web.HttpContext"></see> of the request.</param>
        /// <param name="control">The <see cref="T:System.Web.UI.Control"></see> that the parameter is bound to.</param>
        /// <returns>
        /// An <see cref="T:System.Object"></see> that represents the updated and current value of the parameter.
        /// </returns>
        /// <exception cref="T:System.ArgumentException">The <see cref="P:System.Web.UI.WebControls.ControlParameter .ControlID"></see> property is not set.- or -The <see cref="P:System.Web.UI.WebControls.ControlParameter .PropertyName"></see> property is not set and the <see cref="T:System.Web.UI.Control"></see> identified by the <see cref="P:System.Web.UI.WebControls.ControlParameter .ControlID"></see> property is not decorated with a <see cref="T:System.Web.UI.ControlValuePropertyAttribut e"></see> attribute. </exception>
        /// <exception cref="T:System.InvalidOperationException"><see cref="M:System.Web.UI.Control.FindControl(System.S tring)"></see> does not return the specified control.- or -The control identified by the <see cref="P:System.Web.UI.WebControls.ControlParameter .ControlID"></see> property does not support the property named by <see cref="P:System.Web.UI.WebControls.ControlParameter .PropertyName"></see>. </exception>
        protected override object Evaluate(System.Web.HttpContext context, System.Web.UI.Control control)
        {
            if (control == null) return null;
            if (control.Page == null) return null;


            Control c = this.FindControlInContainer(control.Page);
            if (c==null)
                throw new HttpException("Control '" + ControlID + "' not found.");
            PropertyInfo prop = c.GetType().GetProperty(PropertyName);
            if (prop == null) throw new HttpException("Property '" + PropertyName + "' not found in type '" + c.GetType() + "'.");

            return prop.GetValue(c, null);

        }

        /// <summary>
        /// Finds the control in container.
        /// </summary>
        /// <param name="container">The container.</param>
        /// <param name="controlId">The control id.</param>
        /// <returns></returns>
        private Control FindControlInContainer(Control container, string controlId)
        {
            if (container.FindControl(controlId) != null)
                return container.FindControl(controlId);
            foreach (Control c in container.Controls)
            {
                Control controlFound = FindControlInContainer(c, controlId);
                if (controlFound != null)
                    return controlFound;
            }
            return null;
        }


    }
}

Used in my page as follow :
<asp:ObjectDataSource ID="ObjectDataSource2" runat="server" SelectMethod="..." TypeName="...">
            <SelectParameters>
                <cc1:CrossContainerControlParameter ControlID="GridView1" DefaultValue="..." Name="shortName"
                    PropertyName="SelectedValue" Type="String" />
            </SelectParameters>
        </asp:ObjectDataSource>

Refer to the control parameter like this:
FormView1$DropDownlist1

This is a much easier solution.

I added "Container's ID"+"$" before ControlID already but problem still exist. did you solved the broblem?

Part of the fix to this problem is finding the ID the nested control is given at runtime.

Apply the trace attribute to your page then run it. Scroll through control hierarchy and you should find the control you're dealing with, Pay attention to the system made ID.