IE png images problem

Hi guys,
I checked this website

http://www.iwebsource.com/index.jsp

HTML:

in browsershots and unfortunately the png´s in IE6 show a grey background around.

So I inserted in the head this coding that it worked in other sites before

<!--[if lte IE 6.0]><script defer type="text/javascript" src="{TEMPLATES_DIR}pngfix.js"></script><![endif]-->

HTML:

but it doesnt work for this site.

Any ideas why?
Do you know other way to fix the transparency problem for png´s in IE6?

thanks