title: Why do I get, "Cannot bind to the new display member." with this code?
body: <p>I have this code to assign the values of a Dictionary to a combo box:</p>
  
  <pre><code>private void PopulateComboBoxWithSchedulableWeeks()
  {
      int WEEKS_TO_OFFER_COUNT = 13;
      BindingSource bs = new BindingSource();
      Dictionary&lt;String, DateTime&gt; schedulableWeeks = 
  GetWeekBeginningsDict(WEEKS_TO_OFFER_COUNT);
      bs.DataSource = schedulableWeeks;
      comboBoxWeekToSchedule.DataSource = bs;
      comboBoxWeekToSchedule.DisplayMember = "Key";
      comboBoxWeekToSchedule.ValueMember = "Value";
  }
  
  public static Dictionary&lt;String, DateTime&gt; GetWeekBeginningsDict(int 
      countOfWeeks)
  {
      DateTime today = DateTime.Today;
      int daysUntilMonday = ((int)DayOfWeek.Monday - (int)today.DayOfWeek + 7) 
          % 7;
      DateTime nextMonday = today.AddDays(daysUntilMonday);
      Dictionary&lt;String, DateTime&gt; mondays = new Dictionary&lt;String, DateTime&gt;
  ();
      if (!IsAssemblyOrConventionWeek(nextMonday))
      {
          mondays.Add(nextMonday.ToLongDateString(), nextMonday);
      }
  
      for (int i = 0; i &lt; countOfWeeks; i++)
      {
          nextMonday = nextMonday.AddDays(7);
          if (!IsAssemblyOrConventionWeek(nextMonday))
          {
              mondays.Add(nextMonday.ToLongDateString(), nextMonday);
          }
      }
      return mondays;
  }
  </code></pre>
  
  <p>At runtime, I get, "<em>Cannot bind to the new display member.</em>" with this code, though, on this line:</p>
  
  <pre><code>comboBoxWeekToSchedule.ValueMember = "Value";
  </code></pre>
  
  <p>Why?</p>