title: Session item always null in asp.net mvc3
body: <p>The function to upload image:</p>
  
  <pre><code>        [HttpPost]
          public String UploadSingle(HttpPostedFileBase imageFile)
      {
          try
          {
              String fileSavePath = Server.MapPath("~/Content/Temp/" +
                 imageFile.FileName);
              imageFile.SaveAs(fileSavePath);
  
              List&lt;String&gt; uploadedFile = (List&lt;String&gt;)HttpContext.Session["UploadedFiles"];
              if (uploadedFile == null)
              {
                  uploadedFile = new List&lt;string&gt;();
              }
  
              uploadedFile.Add(fileSavePath);
              HttpContext.Session["UploadedFiles"] = uploadedFile;
              return "Success";
          }
          catch (Exception e)
          {
              return "Error";
          }
      }
  </code></pre>
  
  <p>This function work okay, the image is uploaded. But when i try to see the uploaded images.</p>
  
  <pre><code> public String UploadResult()
      {
          List&lt;String&gt; uploadedFile = (List&lt;String&gt;)HttpContext.Session["UploadedFiles"];
  
          return uploadedFile.Count + "";
      }
  </code></pre>
  
  <p>When i debug, the HttpContext.Session["UploadedFiles"] always return null.
  Please give me some help.</p>