[Plugin: Related Posts Thumbnails] NextGallery non compatibility?

Plugin works great, thank you!

However it does not show images added via NextGen Gallery. For example

If thumbnail is uploaded like this
http://21.maidan.org.ua/wp-content/gallery/cache/76__100x100_golubky.jpg – it shows as broken on replated posts
Thumbnails like this (uploaded via media library)
http://21.maidan.org.ua/wp-content/uploads/2011/07/spihotech-158330035-150×112.png – are shown ok

You can see it here
http://21.maidan.org.ua/2011/06/verhovnu-radu-ukrajiny-do-knyhy-rekordiv-ginnesa/
(all posts have featured images)

Can this be fixed somehow?

Thank you

http://ww.wp.xz.cn/extend/plugins/related-posts-thumbnails/