JQuery :: IE8 Does Not Take Effect While Replacing HTML Tag

I have following jquery, which clicking a anchor link to load a content and replace the h1 to h2 tag in the loaded content before replacing a div content on current page.
$('.previous-news li a').click(function() {
var url = $(this).attr('href');
var link = this;
$('.attachment-content').fadeOut("slow");
$.get(url, function(data) {
var $fullcontent = $('#main-content', data);
var html = $fullcontent.html().replace(/h1/g,"h2");
$(link).parents('.view-content').parents('.view-dom-id-2').find('.attachment .attachment-content').html(html);
});
$('.attachment-content').fadeIn("slow");
return false;
});
It works on firefox and webkit browsers but not in IE8 or 7. H1 tag is not replaced.