Interactive content won't work when you try to run it through an Inquisit script, displayed as <html> or <htmlpage> element. Under Windows, Inquisit in essence embeds Internet Explorer to render HTML, but Internet Explorer imposes certain additional restrictions when run in embedded mode. That, in a nutshell, is why the page doesn't work when you try to run it through Inquisit, but does work when you visit it directly in Internet Explorer (or a different browser).
What you should do instead is _re-direct_ your participants to that site directly in their browser / outside of Inquisit at the end of the Inquisit portion of your study. You can do this by setting the defaults.finishpage property to the desired address in your script (see e.g. https://www.millisecond.com/forums/Topic23033.aspx