Watermark image

Cannot make an image a Watermark.

I have all the latest plugins. Set the image path for the Watermark, I don’t get a preview, and when I go through the gallery and apply the watermark the old text one remains. When I go through the thumbnails it puts the text version on them!

Please can you help

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