I finding that when you click on the image it opens (if large enough) behind the header image. If you scroll down far enough it does solve the problem but that's not really a solution.
I did notice this discussed vs. a couple other gallery plugins but not the Bestwebsoft one.
My test site: http://betatest.ad-creative.com/
(the image titled "map" will go behind the header unless you scroll way down.)
Thank you for your support.