Anyone know how?

I added a folder: C:\ProgramData\Philips\ProntoEdit Professional 3\Gallery\Buttons\Bert

I added some .png images like 'Button1_R.png' and 'Button2_P.png'.
In PEP I see a new category 'Bert' but without images.

What am I doing wrong?

I have created some pages in the config where the buttons are located, and I know I can replace an image of a button, but I am wondering f I could add them to my gallery. Since I can have only 1 page open at the time in the editor shift+drag to copy an image between pages is impossible.