I got a Facebook Page Tab App (using Timeline). It works fine in desktop version of Facebook, but when its Wall Post is clicked in Facebook App, it returns "The page you requested was not found" and forwards to an inaccessible link:
https://m.facebook.com/4oh4.php?id=282832318433409&_rdr
How come? I don't expect mobile version will be the same as desktop version, but I don't expect it reports the page cannot be found.
Page tabs apps are not supported (as of April 2012 anyway) on mobile browsers - mobile apps are, but they're not tied to the Page and need to be manually linked-to or bookmarked, the tab functionality simply doesn't exist now.
Tabs aren't supported via the app or mobile site. Best you could do is add the query parameter "ref=ts" to prevent the page from switching to mobile. It helps in the browser but not the app itself.
So add ?ref=ts to the end of your app url and at least mobile users can see it in their browser.
You can work around this problem by using a Canvas Page to redirect mobile users to a mobile site and desktop users to the page tab.
Detailed instructions here: https://stackoverflow.com/a/15860533/121285
You can access to your app using the next link https://apps.facebook.com/YOUR-APP-ID
In this way, you can access from a desktop or a mobile with no problem
来源：https://stackoverflow.com/questions/9979577/facebook-sdk-page-tab-app-returns-not-found-in-mobile-facebook-app