Donation button not showing

i use this shortcode

[paypal-donation purpose=”my purpose” button_url=”https://visitgreecetips.eu/wp-content/uploads/2015/08/restaurant-300×200-150×100.jpg”]

if I put the same image url in plugin defult setting, it shows my custom test button.

any advice?

https://www.ads-software.com/plugins/paypal-donations/