[TYPO3] pdf_generator2 on TYPO3 4rc2

[lukas.rueegg [pixworx multimedia]]

hi

i'm trying to get pdf_generator2 running but always get the following 
error if accessing the ../index.php?type=123 page:

PHP Fatal error:  Call to undefined function:  getfontascender() in 
/DOCUMENT_ROOT/htdocs/typo3conf/ext/pdf_generator2/html2pdf/output.fpdf.class.php 
on line 132

i'm working with TYPO3 4rc2, templavoila and installed the following 
extensions:

* tv_pdfgen
* pdf_generator2
* fpdf

thanks for any hints.
lukas.