title: Ordering issue with date values when creating pivot tables
body: <p>I have a 2-column spreadsheet which contains <strong>Dates</strong> and <strong>Sales</strong> figures as follows:</p>
  
  <p><img src="https://i.stack.imgur.com/o78In.png" alt="enter image description here"></p>
  
  <p>When doing <strong>Right click -> Format Cells</strong> the values in the <strong>Dates</strong> column properly appear as <strong>Date</strong> (in the <code>M/D/YYYY</code> format). This applies to all the Dates cells with the exception of the header (I checked with Ctrl+Shirt+Down).</p>
  
  <p>However when I create a pivot table from the 2 columns, the <strong>Dates</strong> are recognized as text and are sorted accordingly (i.e. 1st sorted by month, then by day, then by year) which messes up my data:</p>
  
  <p><img src="https://i.stack.imgur.com/XDw6u.png" alt="enter image description here"></p>
  
  <p>I create pivot tables with this type of data on a regular basis and never had this issue before, and I really don't see what's wrong there.</p>
  
  <p><strong>How can I force the date values to be recognized as such when creating pivot tables?</strong></p>
  
  <p>PS: I have uploaded the <a href="http://ge.tt/83D38tY/v/0?c" rel="noreferrer"><code>pivot_table_date_porder_issue.xlsx</code></a> file which exhibits the problem for whoever wants to see it.</p>