Problem to convert PDF to JPG

[JH_mijn]

Hi,

Can you help me with the following problem.
I use this line in a script: exec("convert ".$form_pdf." ".$to_jpg);

When i convert "pdf_wel.pdf" the script works fine and gives me a correct jpg file.
Almost the same pdf, pdf_wel.pdf", gives me nothing.

Can somebody tell me the difference.

Regards,
Jeroen

[JH_mijn]

Extra information:

There is a difference between the pdf develop-programs.
When a pdf is printed by a standard Adobe Acrobat Distiller 7.0.5., the image is ok.
In all other programs will the script return nothing or a give a empty image.


Regards,
Jeroen