mod_rewrite directives- do'nt work in server config context?

[flex55]

hi guys,

i have the following simple rewrite directives:

RewriteEngine on
RewriteCond %{HTTP_USER_AGENT} ^aaa
RewriteRule ^.* http://www.domain.com [L]

now, it works well on the <virtualhost> directive-
but as I want to apply it to all virtualhosts, i want to put it in server config- yet it doesn't work, for some reason, in the server config.

I tried to add RewriteOptions inherit to all virtualhosts, but no luck
does anyone have an idea?

thanks!
f.