[GNC] No PDF button

[nco2018 at outlook.com]

I have been using gnucash for about 7 months on linux mint without any 
problems but have recently installed in on a mint 20 machine. The 
problem now is there is no way of producing a pdf of the invoice I've  
created, the PDF button is missing. I have also tried installing older 
versions but always get the same gui without a pdf button.

help would be very much appreciated, dig