htaccess redirect subdomain
===

I have the following .htaccess code:

    <IfModule mod_rewrite.c>
    
    RewriteEngine On
    RewriteCond %{HTTP_HOST} !^www.mysite.co$ [NC]
    RewriteRule ^(.*)$ http://www.mysite.co/$1 [R=301,QSA,L]
    
    </IfModule>

The problem is that all subdomains get redirected to www.mysite.co/subdomain
How can I aviod this?