title: Output() in fpdf does not work
body: <p>I am trying to generate a pdf file containing pie charts. By i am having the following Error:</p>
  
  <p><strong>FPDF error: Some data has already been output, can't send PDF file</strong> </p>
  
  <p>After fighting for about an hour I found out that it works pretty well with: <em>Output("Report.pdf",'F');</em> but shows error message with: <em>Output();</em>.</p>
  
  <p>So I am stuck here...can anyone help me with this situation ?</p>