Can't set comboBox value that has valueMember / displayMember

Question

Hello All,
I'm working on a project where I'm dynamically building a form according to a configuration schema. I'm pretty new at C# and got the following issue I can't get sorted out . 
Any help, advise would be great !!!
When building a ComboBox I can't set the value I want !!
Probably I'm missing something.
I've tried several methods but nothing does it ... below my code.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace ComboBoxSample
public partial class Form1 : Form
public Form1()
InitializeComponent();
CreateComboBox();
public void CreateComboBox(){
//Working variables
string valueMember = "idColumn";
string displayMember = "valueColumn";
//Create a panel and add to the form
TableLayoutPanel tlp = new TableLayoutPanel();
this.Controls.Add(tlp);
//Create the data source
DataTable dataTable = new DataTable();
dataTable.Columns.Add(valueMember, typeof(string));
dataTable.Columns.Add(displayMember, typeof(string));
dataTable.Rows.Add("A", "value A");
dataTable.Rows.Add("B", "value B");
dataTable.Rows.Add("C", "value C");
//Create a binding source
BindingSource bindingSource = new BindingSource(dataTable, null);
//Create a comboBox and bind the datasource
ComboBox comboBox = new ComboBox();
comboBox.DropDownStyle = ComboBoxStyle.DropDownList;
comboBox.DataSource = bindingSource;
comboBox.ValueMember = valueMember;
comboBox.DisplayMember = displayMember;
Try and set the value
//No methode displays B --> combo stays on A
comboBox.SelectedValue = "B";
//comboBox.Text = "value B";
//comboBox.SelectedItem = comboBox.FindStringExact("value B");
//add the controles to the panel
tlp.Controls.Add(comboBox, 0, 0);

Answer 1

Hi Viorel_,
Thanks for the reply!!
The  setting the value in the form's Load event does work!
I agree for the form designer but it does not fit the need.
What I have is a "meta-data" driven logic where I define a screen that matches database fields:
Example : Screen new person has 5 fields : Gender (combobox) , first name (textbox) , last name (textbox) , type (combobox) ,birthday (datetime)
I have a Form derived class that takes this definition and builds each control at run time.
The definition also comes with potential default values (i.e. :type = client) so what I want to do is affect the value on the fly. This works fine with textbox or datetime. I'm trying to do the same for combobox.
Maybe I got this all wrong from a design point of view.