ServletException: MultipartIterator

[hunkpapa]

Hi,
when I start this program this message comes:
action: Error in readForm: javax.servlet.ServletException:
MultipartIterator: cannot retrieve boundary for multipart request
What is the cause ?
...
 if(contentType!=null)
 {
  try
  {
   servlet.log("MultipartIterator!!");
          MultipartIterator iterator = new MultipartIterator(request);
          MultipartElement element;
          while ((element =(MultipartElement) iterator.getNextElement())
!= null)
          {
           servlet.log("element.getName() " +element.getName());
           servlet.log("element.getFileName() " +element.getFileName());

           servlet.log("element.getContentType() "
+element.getContentType());
           servlet.log("element.getData() " +element.getData());

              //do something with element
          }
  }
  catch(Throwable t)
  {
   System.out.println("Error in readForm: "+t.toString());
   }
}
..