invoice print out has small font

-- HikaShop version -- : 2.3.3
-- Joomla version -- : 2.5.27
-- Browser(s) name and version -- : Firefox 33.0

Hello,
I really don't know since when this is happenend, but today I tried to print an invoice.
The look of the preview (see invoice-1.JPG) seems to be ok, but when I actually print the invoice (see invoice-2.pdf) the fonts seems to be smaller like everything was shrinked and the supplier address is not an the right place where it should be.

I use a modified invoice.php (version 2.3.1). For test reason I also copy the current 2.3.3 invoice.php; it's the same problem.

I really don't know what it is: php, pdf generater or my printer driver.
Can you help me?

Kind regards,

Marco