title: Warning: openssl_pkcs7_sign() [function.openssl-pkcs7-sign]: error getting private key in C:\xampp\htdocs\this\tcpdf\tcpdf.php on line 8366
body: <p>I am using TCPDF to sign PDF, but when running the <a href="http://www.tcpdf.org/examples/example_052.phps" rel="nofollow">example 52</a> I got this error:</p>
  
  <pre><code>Warning: openssl_pkcs7_sign() [function.openssl-pkcs7-sign]: error getting 
  private key in C:\xampp\htdocs\this\tcpdf\tcpdf.php on line 8366
  </code></pre>
  
  <p>Could you please tell me or guide me where is the problem. I am just running the example without changing anything. I am using xampp.</p>