“No output” is meant literally. The body of the HTTP response contains 0 (zero) bytes, there are only headers sent which seem to be quite normal:
HTTP/1.0 200 OK
Date: Sun, 03 Mar 2013 14:25:11 GMT
Server: Apache/2.2.16 (Debian)
X-Powered-By: PHP/5.3.3-7+squeeze14
X-Pingback: http://www.vienna-style.at/xmlrpc.php
Vary: Accept-Encoding
Content-Length: 0
Connection: close
Content-Type: text/html; charset=UTF-8
