title: dataset does not support system nullable in crystal reports
body: <p>I am using vs2012 asp.net mvc and crystal reports v.13.</p>
  
  <p>i have this error when i am trying to export the crystal report</p>
  
  <blockquote>
    <p>DataSet does not support System.Nullable&lt;>.</p>
  </blockquote>
  
  <p>at this line  </p>
  
  <blockquote>
    <p>rd.SetDataSource(cn.Customers.Select(c => new</p>
  </blockquote>
  
  <pre><code>    public ActionResult Index()
      {
          ViewBag.listCustomers = cn.Customers.ToList();
          return View();
      }
      public ActionResult Export()
      {
          ReportDocument rd = new ReportDocument();
          rd.Load(Path.Combine(Server.MapPath("~/Reports/CustomerReport.rpt")));
          rd.SetDataSource(cn.Customers.Select(c =&gt; new
          {
              CustomerID = c.CustomerID  ,
              CustomerName = c.CustomerName ,
              CustomerEmail = c.CustomerEmail ,
              CustomerZipCode = c.CustomerZipCode ,
              CustomerCountry = c.CustomerCountry ,
              CustomerCity = c.CustomerCity,
          }).ToList());
  
          Response.Buffer = false;
          Response.ClearContent();
          Response.ClearHeaders();
          Stream stream = rd.ExportToStream(CrystalDecisions.Shared.ExportFormatType.PortableDocFormat);
          stream.Seek(0, SeekOrigin.Begin);
  
          return File(stream, "application/pdf", "CustomerList.pdf");
    }
  </code></pre>
  
  <p>this is the view:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;table&gt;
      &lt;tr&gt;
          &lt;td&gt;CustomerID&lt;/td&gt;
          &lt;td&gt;CustomerName&lt;/td&gt;
          &lt;td&gt;CustomerEmail&lt;/td&gt;
          &lt;td&gt;CustomerZipCode&lt;/td&gt;
          &lt;td&gt;CustomerCountry&lt;/td&gt;
          &lt;td&gt;CustomerCity&lt;/td&gt;
      &lt;/tr&gt;
      @foreach (var cust in ViewBag.listCustomers)
      {
          &lt;tr&gt;
              &lt;td&gt;@cust.CustomerID&lt;/td&gt;
              &lt;td&gt;@cust.CustomerName&lt;/td&gt;
              &lt;td&gt;@cust.CustomerEmail&lt;/td&gt;
              &lt;td&gt;@cust.CustomerZipCode&lt;/td&gt;
              &lt;td&gt;@cust.CustomerCountry&lt;/td&gt;
              &lt;td&gt;@cust.CustomerCity&lt;/td&gt;
          &lt;/tr&gt;
      }
      &lt;br /&gt;
      &lt;br /&gt;
      &lt;a href="@Url.Action("Export","Customer")"&gt;Export report&lt;/a&gt;
  
  &lt;/table&gt;</code></pre>
  </div>
  </div>
  </p>