custom tab content doesn't show up in facebook page

I created a facebook page for my company and we wanted to add a custom tab for u开发者_如何学Pythonsers to land on. I went and created an app to do an iframe tab since fbml has been depreciated. Anyway i have everything set and added the app on the fan page, but when you click on the link for the custom tab nothing shows up in the content area.

Any ideas as to why this is happening? I can see the content just fin on our server, it just doesn't load inside the facebook page

I have the same problem (FF 3.6, IE8). I've discovered that the Custom app/tab won't display in the my FB page if I'm logged into my own page. The only "solution" I have found is to log out of FB, or open a different browser and display the page "anonymously". Only then does the custom tab appear.