Hi Anita,
Actually we have already opted out from the support of IE 6 – 8. However, our plugin should work fine in those browser. Recently i tested with Ie 8 (http://www.masonrylayout.com/masonry-theme-demo/fishtail/) and it is working fine.
Any chance you can send me your site url as well ? We will check it from here. And try to find out the issue.
Thanks