Yahoo indexing www and non www

But I have proper 301 redirects

[taps]

My site is not ranking well at yahoo. Maybe it is because of some kind of dupe content problem.

When searching for my site I see results from www.widget.com as well as from widget.com. However I do not see the same article indexed with both adresses. Some are www, some are non-ww

I don't know how that could happen since I have installed a 301 redirect:

RewriteCond %{HTTP_HOST}!^www\.example\.com$
RewriteRule ^(.*)$ http://www.example.com/$1 [R=permanent,L]

Using a header checker I can see a proper 301 redirect.

The redirect exists since Feb 2005 and it seems to work very well for google and other search engines.

I see the problem with all my sites based on a self written cms. Any idea what could be wrong?

[edited by: martinibuster at 9:37 pm (utc) on April 9, 2006]
[edit reason] examplified [/edit]