Canvas Question: Pinterest Widgets

Don't ask me why, but the only way you can display a Pinterest Board is to create your own HTML file, insert the javascript, and then upload that file. The javascript in the file works, but the same javascript in a Canvas page will not work? Perhaps a Canvas guru can enlighten me about that!

This link takes you to the file so can see what I mean: pinterest.html.

FWIW you can also see that the Pinterest Board renders if it is inserted into a Blogger blog post which is embedded via iframe.

But when I put the exact same content of the HTML file into a Canvas page, the Pinterest Board does not display. You can see the result here: Pinterest test page.