Facebook development problem on return canvas url

I have an application i.e apps.facebook.com/myappnamegoeshere/

Its canvas URL is i.e subdomain.mysite.com

When Facebook wants to authenticate me it returns my canvas URL, but it addssomething like this to my URL:

subdomain.mysite.com/amegoeshere/?authtoken=bla bla...

My page gives 404 error, naturally.

Does anyone know how to fix this?开发者_如何学Python

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Make sure your facebook application settings are correct and the canvas call back url is what you want it to be.

-Roozbeh