I've followed this tutorial to create a custom page on some facebook pages; now the problem is that some people can't see anything: they can see only a blank page inside facebook
The pages are:
https://www.facebook.com/AmbassadorRicevimenti (clicking on Home tab some people can't see my html page)
https://www.facebook.com/pages/Le-torte-di-Antonietta/173602889364785 (clicking on Home tab some people can't see my html page)
For these pages I've got both https and http urls; I've even tried to put only "hello word" in these pages, but nothing, some people can't see anything.
Obviously sandbox mode is off, so everyone can see the page.
I've seen that this blank page happens both with facebook logged users, and with not logged users (so people that tries to see the page without logging on facebook, but using a direct link); many other people (logged and not) can see the page without problems.
For me it looks like the Secure Page Tab URLs for your Tab Application are working fine, but your Page Tab URLs are not. For both of the Facebook pages you shared, I can see your App content if I'm browsing over https but not for http. On both pages I see the error message "Loggati su Facebook per vedere questa pagina. Grazie mille," when viewing the Tab over http. (This translates to "Log into Facebook" in Italian, but I am logged in.)
Are your sure the http URL is working properly?
Do you have any App settings or features in your http URL that would break the page when it is viewed over http instead of https?