Trying to exclude category from index/blog page (homepage is static)

Hi thanks for viewing.

I am using a category ‘testimonials’ for a testimonoials page, so i want the posts in category testimonials excluded from the main blog page.
i am using
`<?php query_posts($query_string . ‘&cat=-3′); ?>’

and am pretty sure the category id is 3 as when i hover over it in categories page it show tag_ID=3.

the blog is still showing the testimonials though. Anything i’m missing?

Many Thanks

Frank