title: FPDF error: Some data has already been output, can't send PDF file
body: <p>well I get this error trying to use php class FPDF:</p>
  
  <pre><code>FPDF error: Some data has already been output, can't send PDF file (output started at
  /mnt/webc/e1/12/5691512/htdocs/adminpanel/fpdf/test.php:1)
  </code></pre>
  
  <p>My test.php</p>
  
  <pre><code>&lt;?php
  require_once("fpdf.php");
  $pdf = new FPDF();
  $pdf-&gt;AddPage();
  $pdf-&gt;SetFont('Arial','B',16);
  $pdf-&gt;Cell(40,10,'Hello World!');
  $pdf-&gt;Output();
  ?&gt;
  </code></pre>
  
  <p>There are no blanks or anything... So where is the error???</p>