Broken Relationship between posts

Hello,
I am using a script to automatically post images I upload: http://ww.wp.xz.cn/extend/plugins/automatic-featured-image-posts/
And that worked well. Except that after playing around a little bit and deleting some images & corresponding posts some of the relationships between the posts are broken.
So for example there is no previous button eventhough there are older posts. Or When I click next it skips a post, and shows me the one after it.
My question is, where is the relationship between Posts stored. Where is it defined which post comes after or beofre another?
I exported All my content to an xml file from the Admin Panel, but can’t seem to find that information there. If it isn’t possible through the xml import/export can you tell me where in the database I can edit that information?
Since it is only a handful of posts that are broken, I would like to manually fix.
Problem example can be found here:
http://www.davidgoering.com/?p=301 should have a Previous button, and the image before that links to the Image after:
http://www.davidgoering.com/?p=299 (Next should jump to 301 not 303)
Hope somebody can help me.
Thanks in advance!

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