add gallery with the button in a post & select image from nextgen gallery

Hi,

I try to add a gallery with the button when I am writing a post.

But when select “Select or enter gallery” the list of my galleries doesn’t appear.

The second problem is when I want to add a featured image, I want to select an image from Nextgen gallery but when i select the gallery (yhere the names appears) but after it doesn’t load any image.

Somebody can help me to resolved this two problems?

Thanks you very much

https://www.ads-software.com/extend/plugins/nextgen-gallery/