wp-cufon browser issues

I’ve installed the wp-cufon plugin but it only seems to work in Safari and Chrome. It’s applied to page headings (#page_heading h1) for testing but does not display in IE7, IE8 and FF3.5? I’ve used cufon on non-Wordpress sites and it works in these browsers. Are there known issues with wp-cufon and certain browsers? Any suggestions would be appreciated.

http://casalucia-tuscany.com/sitev2/