Google Plus icon not showing - “Display forbidden by X-Frame-Options”

I've been trying to add a google plus icon to my webpage but I haven't been able to make it work. I use HTML5 and I have tried doing this:

I added the following <script> before the </body>

<script src="http://ift.tt/xnjN8S"></script>

and this in the place I want it to be shown.

<g:plusone size="tall" count="true"></g:plusone>

but I get the following error

Refused to display 'http://ift.tt/1E0qSnV…refresh&id=I0_1425069928860&parent=file%3A%2F%2F&pfname=&rpctoken=36362517' in a frame because it set 'X-Frame-Options' to 'SAMEORIGIN'.

I also checked this question but the &output=embed solution isn't working for me.

I was able to use the facebook and twitter share using iframe but I can't find an example for doing the same for the google +1.

NOTE: The page I'm making is part of an assignment and it's not supposed to be online until after the deadline. I don't know if the problem is because the page is still local on my computer.