WordPress kills an IFRAME’s apostrophes

I’m using an IFRAME to let multiple sites embed one interactive element. On the IFRAME’s actual page it works fine, and it looks fine on another website I embedded it. But when I embed it in a WordPress blog, all my apostrophes show up as squares.

I tried removing all smart quotes and apostrophes with “dumb” quotes, no luck.

I tried replacing all the apostrophes with ‘ and, again, no luck

Any clues what my cause this?

The IFRAME code:

<iframe
  src="http://necir-bu.org/wp/interactives/sheriffinteract/interactive.html"
  name="interactive" scrolling="no"
  frameborder="0" marginheight="5"
  align="center" vspace="5"
  widtha"590px" height="720px"></iframe>

And you can see the interactive code by just viewing the first link