There must be an incorrect setting with your facebook App.
Can you check you facebook app settings ? Check your exact facebook app version >=2.7.
Let me know.
- Need help? Post the URL of the related page (eventualy as confidential info), it will help solve your issue faster.
- An error, notice or warning? report the exact message including the line number
- If you get a white page , enable error reporting and / or check your server error logs.