sIFR onReplacement callback not working on win/IE or win/FF

Question

I am trying to invoke a callback function from my sIFR config file using onReplacement. It works fine on Mac (Safari and FireFox), but not on Win/IE7 or Win/FireFox (note: I'm using Vista).

Here is my config code:

sIFR.replace(museoslab_300, { selector: '.fs', css: '.sIFR-root { background-color: #FFFFFF; color: #E31937; padding: 0; margin: 0; }', wmode: 'transparent', forceSingleLine: true, onReplacement: function() { alert('hello world'); } });

I'm using sIFR 3, r436. Any ideas?

Thanks! -becca