Editor not loading when using xml mime type

Hi,

I am using FCKeditor with PHP. My pages are XHTML 1.1, and thus I am using the "application/xhtml+xml" MIME type for all my pages.

I have this in top of my PHP pages:

header("Content-Type: application/xhtml+xml; charset=ISO-8859-1");

However, this causes FCKeditor to not load (none of the toolbars show up).

When I remove the line, it works. What can I do to make it work with the application/xhtml+xml mime type?

Thanks.