facebook app does not show turn off https

I create a simple facebook app, and when users with https navigate to that, the dialog that alert them about turning off https, does not appear. just a blank page shown and nothing else. can help开发者_高级运维 me please?

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Check you application settings under Settings->Basic "App on Facebook".

There is option "Secure Canvas URL".

This is the url that you application is redirected when users are using HTTPS.

Hope that helps.