title: PHPEXCEL getCalculatedValue or getFormattedValue returns fatal error
body: <p>I have a file with mime-type "application/octet-stream; charset=binary" and extension ".xlsx". PHPExcel_IOFactory::identify($this->file) returns 'Excel2007'. I create my reader like this:</p>
  
  <pre><code>$this-&gt;objectReader = PHPExcel_IOFactory::createReaderForFile($this-&gt;file);
  </code></pre>
  
  <p>When I try to get a cell value with a formula I can only do it in two ways:</p>
  
  <pre><code>1)$sheet-&gt;getCell($columns[$i].$row-&gt;getRowIndex())-&gt;getValue() 
  //return the actual formula as a string
  2)$sheet-&gt;getCell($columns[$i].$row-&gt;getRowIndex())-&gt;getOldCalculatedValue() 
  //returns the oldCalculated value which is not always corret (for example the value in the cell is 17.4% and it returns 0.17)
  </code></pre>
  
  <p>When I dump the $sheet->getCell($columns[$i].$row->getRowIndex()) object the output starts with the fallowing : </p>
  
  <pre><code>object(PHPExcel_Cell)[142370]
    private '_value' =&gt; string '=IFERROR(IF(C$6="yes",IF(ISBLANK(INDIRECT(ADDRESS($AN15,MATCH($B$6,INDIRECT("'"&amp;C$7&amp;"'!"&amp;$AN$9-1&amp;":"&amp;$AN$9-1),0),,,C$7),TRUE)),"",INDIRECT(ADDRESS($AN15,MATCH($B$6,INDIRECT("'"&amp;C$7&amp;"'!"&amp;$AN$9-1&amp;":"&amp;$AN$9-1),0),,,C$7),TRUE)),""),"")' (length=231)
    private '_calculatedValue' =&gt; float 0.1744360902255639
    private '_dataType' =&gt; string 'f' (length=1)
    private '_parent' =&gt;...
  </code></pre>
  
  <p>The correct value is there but I can't access it...
  When I try to get the cell value with getFormattedValue() or with getCalculatedValue() the output is the fallowing fatal error: </p>
  
  <pre><code>Catchable fatal error: Argument 2 passed to PHPExcel_Calculation_LookupRef::INDIRECT() must be an instance of PHPExcel_Cell, boolean given
  </code></pre>
  
  <p>Any idea of how to solve this problem ? I am really stuck and have no idea. Thank you.</p>