W3C Iframe Validation

Question

Hello.

I'm using the Facebook plugin called Activity Feed.

The URL of this plugin is: http://developers.facebook.com/docs/reference/plugins/activity

Now, I'm having a problem.

When I get the code for using this plugin it comes inside an IFrame, and has a not standard attribute for Internet Explorer browsers, or at least that what I read, it's the allowTransparency="true" attribute.

When I validate my web site with this component it shows an error, there is no attribute "allowTransparency".

http://validator.w3.org/check?uri=http%3A%2F%2Fwww.ollivanders.co%2F&charset=%28detect+automatically%29&doctype=Inline&group=0

How can I solve it?

Thanks!!