If you are seeing "permissions" errors in your log, It looks like your app hasnt been granted the correct permissions for your fanpage.
Please try creating a new app and re-install it following the tutorial #2 Setup + App Creation
Pay close attention to the part where I click the "auth" link and say yes numerous times in the pop-up box to grant all the correct permissions.
You need to make sure you follow that tutorial exactly, as it seems like you have made a mistake doing this.
ALSO please create a new fanpage for your site and select it from the dropdown menu in the "settings" page, remember to save changes.
Creating a brand new app and brand fanpage and using them both together gives you the best chance of resolving this issue.
Finally we also recommend resetting comments, particularly if you have been using the default comments. please go to your comments and scroll down to the bottom and click "reset defaults".
Once you have reset the comments we highly recommend you alter them, and add your own unqiue ones to make them appropriate for your niche.
If you have tried this and is still doesnt work we can setup your app for you. To do this we will need your facebook login details.