title: Datatable column headers missing when vertical scroll is enabled
body: <p>Below is my datatable initialization</p>
  
  <pre><code>$('table.datatable').DataTable({
      scrollY:        "150px",
      scrollCollapse: true,
      fixedHeader: true,
      bFilter : false,
      paging:         false,
      bLengthChange : false,
      pageLength : 5,
      "language" : {
         "zeroRecords" : "No Requests found"
      }
  });
  </code></pre>
  
  <p>I want to have vertical scroll and no pagination. When i include 'scrollY' for vertical scroll i have the vertical scroll bars, but the column headers are disappearing. If anyone had a similar experience please help me with this.</p>