[jQuery] Append-tag problems in IE7

[julio]

Hi,

I have a document in Iframe retrieved correctly. I would like add a
tag in head-tag. I have tried with:

var head = frameDocument.documentElement.firstChild;
$(head).append("<link rel='stylesheet' type='text/css'
href='selector.css' />");

and:

var head = frameDocument.getElementsByTagName("head")[0];

but it doesn't work.

Have you any idea? I don't know if it's a jquery problem or my
mistake.

Thanks,
Julio