Unable to Access the Dynamic control-Collection of common programming errors

A recursive FindControl might be more helpful if you do have the control’s ID.

public static T FindControlRecursive(this Control parentControl, string id) where T : Control
    {
        T ctrl = default(T);

        if ((parentControl is T) && (parentControl.ID == id))
            return (T)parentControl;

        foreach (Control c in parentControl.Controls)
        {
            ctrl = c.FindControlRecursive(id);

            if (ctrl != null)
                break;
        }
        return ctrl;
    }
// and then: Page.FindControlRecursive(idOfYourControl);