title: Problem while sorting DataTable with LINQ based on DateTime
body: <p>I want to sort a DataTable based on a column which has date value. I was running in to issues so i created following test method:</p>
  
  <pre><code>private static void Test()
      {
          DateTime testDate = DateTime.Parse("01/01/2011");
  
          DataTable table = new DataTable();
          table.Columns.Add("dateValue");
          table.Columns.Add("slNo");
  
          DataRow row1 = table.NewRow();
          row1["dateValue"] = "01/01/2011";
          row1["slNo"] = "1";
  
          DataRow row2 = table.NewRow();
          row2["dateValue"] = "01/02/2011";
          row2["slNo"] = "1";
          DataRow row3 = table.NewRow();
          row3["dateValue"] = "02/01/2011";
          row3["slNo"] = "1";
          DataRow row4 = table.NewRow();
          row4["dateValue"] = "01/03/2011";
          row4["slNo"] = "1";
  
          table.Rows.Add(row1);
          table.Rows.Add(row2);
          table.Rows.Add(row3);
          table.Rows.Add(row4);
  
          var t = table.AsEnumerable().OrderBy(x =&gt; x.Field&lt;DateTime?&gt;("dateValue")).ToList();
      }
  </code></pre>
  
  <p>I get Following error:</p>
  
  <pre><code>Specified cast is not valid.
  </code></pre>
  
  <p>The date provided can be parsed to DateTime object. But still it get the above error. Any idea what is missing?</p>
  
  <p>I use C# 3.5</p>