Validator giving error

I am using galley plugin but when I validate, it give following error.

Bad value gallery_fancybox for attribute rel on element a: The string gallery_fancybox is not a registered keyword or absolute URL.
…//geniusmindgraphics.com/gm/wp-content/uploads/2013/11/bear.png” title=”Bear” >

You can check page below.

http://geniusmindgraphics.com/gm/gallery/web-design-2/

Please any solution? I want to add about 300 images than it will give same number of error. Anyone can help me please?

Atif
http://www.geniusmindgraphics.com

http://ww.wp.xz.cn/plugins/gallery-plugin/