iframe content disappearing randomly

I'm trying to add a Facebook feed box for a Facebook page to a webpage. After trying to use Facebooks' guides I finally gave up, since I don't have an app ID and pasting the javascript in never gained results.

So I followed this brief tutorial: http://ift.tt/1DbqZcc

Here is my end result:

<iframe src="http://ift.tt/1ArS1if" scrolling="yes" style="border:none; overflow:hidden; width:97%; height:540px; background: white; float:left; " allowtransparency="true" frameborder="0">
</iframe>

The feed box displays fine at first. Then it randomly (with no change or edit to the code) disappears. I got it to come back briefly by starting over from scratch in a new file...but shortly after it disappeared again (also with no change or edit to the code).

I have no idea why this is happening. So if anybody has any fix I'd love to hear about it. This is my first attempt trying to embed a Facebook feed box. I'm well versed in HTML & CSS, but not so much in JS so please talk to me as a child if your solution involves JS or any other programming language.

Thanks so much in advance!!