HTMLDOC Problem:

Htmldoc produced no pdf-output.
Commandline:

/usr/bin/htmldoc -t pdf13  --webpage -f /var/www/web2/html/typo/typo3temp/hd_A6aysm - 2>/var/www/web2/html/typo/typo3temp/se_llQ9QL

This is the (stderr) output of the htmldoc command without the htmldoc_append parameters:
If you see no errors here please check your htmldoc_append parameters too.

HTMLDOC(17848) INFO: HTMLDOC 1.8.27 starting in CGI mode.
HTMLDOC(17848) INFO: TMPDIR is "(null)"
HTMLDOC(17848) ERR005: PATH_INFO is not set in the environment!
Can't open display: