richlondon on "no www address redirect issue with IIS on wordpress"

Hi,
I have the site http://www.btl.com which is running on IIS
When someone types in "btl.com" they get redirected to a 404 page, where is trying to find the page http://www.btl.com/www.btl.com

I'm guessing that my web.config file needs some tweaking am I correct?
It currently has the line
"<httpRedirect enabled="false" destination="http://btl.com" childOnly="true" httpResponseStatus="Permanent" />"

when I set it to true the browsers can't get to the btl.com site..

Can someone help please?

thanks in advance

Rich