[TYPO3-install] ImageMagick not reading PDF

[Fabian]

Hello,

I have a TYPO3 installation where everything from ImageMagick is working 
fine except PDF and AI. If I do the image tests in the Install Tool, the 
PDF and AI test both return: "There was no result from the ImageMagick 
operation". If I however copy and paste the dump of commands executed in 
ssh it works fine, the PDF is read and a JPG is generated 
(install_read_pdf.jpg).

I have tried reinstalling ImageMagick and Ghostscript from the ports 
collection (FreeBSD) but the problem persists. I'm using ImageMagick 
6.3.6 and Ghostscript 8.61.

Does anyone have any idea what the problem could be?

Greetings
Fabian