[TYPO3] problem with pdf_generator2

[Andreas Balzer]

Hi! I get the following error in FE when trying to open a static page 
with pagetype 123:

Warning: tempnam(): open_basedir restriction in effect. File(/tmp) is 
not within the allowed path(s): 
(/home/www/kunden/ess-erfurt.de:/usr/share/pear:/tmp/php:/usr/bin) in 
/home/www/kunden/ess-erfurt.de/contents/typo3conf/ext/pdf_generator2/html2pdf/output.fpdf.class.php 
on line 273

Warning: imagepng(): Invalid filename '' in 
/home/www/kunden/ess-erfurt.de/contents/typo3conf/ext/pdf_generator2/html2pdf/output.fpdf.class.php 
on line 274
FPDF error: Can't open image file:

What do i have to do?

Thanks for any help.
Andreas