title: ComboBox Datasource giving exception
body: <p>I have this simple piece of code for populating a <code>ComboBox</code> :</p>
  
  <pre><code> DataSet dt = new DataSet();
  
   dt = db.getCourses(depID, academicYearValue, semID);
   if (dt.Tables[0].Rows.Count &gt; 0)
   {
       dropdownCourses.DataSource = dt.Tables[0];
       dropdownCourses.DisplayMember = "Course";
       dropdownCourses.ValueMember = "ID";
   }
  </code></pre>
  
  <p>I have  4 <code>ComboBoxes</code> on the Form all work with the code above and get populated, only for this <code>ComboBox</code> when populating <code>DataSouce</code> i get exception :</p>
  
  <pre><code>Object reference not set to an instance of an object.
  </code></pre>
  
  <p>And i cannot figure out anything , any suggestions what to look for?</p>