You still need to be more specific because adding/editing in general works fine (I just tested it). Your latest successful POI submission is this one:
http://maps.eq2interface.com/poi.php?id=47399. I assume you are trying to submit similar POIs now and they fail? There must be something about your specific case which is causing this and checking the code I frankly have no idea at this time what that could be.
Therefore a screenshot of the submission page with the data you are trying to submit would be helpful (the page where you get the "save" button). I'll try to figure it out from there. You can upload screenshots as attachments to your posts on these forums.