Same issue as others have had but can't find the solution to it on my theme. "Missing the call to wp_head() in your theme, contact the theme author". The theme is Crumble Magazine from Themeforest. The wp call is both in the head and footer already. When I try to embed an image, especially as a featured image. The gallery works but using any of the Nextgen gallery images on other parts of the theme (slideshows, carousel, featured image) don't show and in some cases when the image URL is called directly, the setting won't keep. I've tried disabling all other plugins and modifying the theme code (re-adding wp calls), reinstalled the theme, etc.
Any ideas or solutions?
BTW, I contacted the author and they referred me back to this forum.