htaccess non www to www and remove subdomain www

htaccess non www to www and remove subdomain www

So I've got the following rewrite code in my htaccess
RewriteEngine On
RewriteCond %{HTTP_HOST} ^[^.]+\.[^.]+$
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [L,R=301]
//
RewriteEngine On
RewriteCond %{HTTP_HOST} ^www\.([^\.]*)\.domain\.com$ [NC]
RewriteRule (.*) http://%1.domain.com$1 [R=301,L]
Works perfect for redirecting non-www to www for my domains.
I've got a subdomain, lets call it 'sub.domain.com' which works find. If I
goto www.sub.domain.com, it redirecting to 'sub.domain.com/sub/' Anyone
having a idea why?