You simply enable lightbox v2 on image nodes (admin/settings/lightbox2) but your lightbox show a small imagecache thumbnail?
- Disable lightbox on image nodes (admin/settings/lightbox2)
- Enable “Display image with a link to the image file” (admin/settings/inline)
- Apply this Inline lightbox patch
This patch simply add a rel=”lightbox” to each inline image link, natively pointing to full-size image.