Apache2 ScriptAlias seems to be ignored

Question

I have two vhosts configured on my Apache2 server. One contains the API and the other a mobile version of my app. Since the mobile version needs to access the API from its own domain, I decided to create a ScriptAlias entry for this. Unfortunately it does not work, so I appreciate any advice on what I did wrong.

<VirtualHost *:80>
    DocumentRoot /path/to/mobile/version/htdocsdir
    <Directory />
            Options FollowSymLinks
            AllowOverride All
    </Directory>
    ScriptAlias /api /path/to/api/htdocsdir
    <Directory /path/to/api/htdocsdir >
            Order allow,deny
            Allow from all
            Options FollowSymLinks
            AllowOverride All
    </Directory>
</VirtualHost>