Clipboard manager: pasted icon not shown

I added a button in Clipboard manager and use a picture from clipboard as the icon. It looks good when defining it like below.

But when I run clipboard manager, the picture is not shown, it just show a black area like below.

How can I show the picture correctly?

the background of the icon either needs to be transparent or it needs to contain color. Whit backgrounds won’t work with BTT at the moment

I tried to make the picture transparent or have background color and both works the same as white background.

Thanks a lot. I tried a transparent picture and it works.

did you use a file format that supports transparency? e.g. png?

It works fine now. Previously I didn't do it correctly.