Facebook have made changes to their API so please upgrade to version 3.1.6 Classipress and it will work.
If you still have issues with 3.1.6 please tell the staff that you already upgrade to the last version.
I love to help out you out but please read this first Have you tried to install in a root domain? Have you tried to Resave permalinks? Have you tried to disable all plug in? Have you tried the default theme of Wordpress?
++ If the issue is fixed consider closing the thread and change to solved, thank you for helping us helping you. ++
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