Installing fails due to data directory

Hi,

I'm trying to install elgg on my webserver.

The Web-Root is /var/www/vhosts/example.com/httpdocs/ where all elgg files were installed.

I created a folder /var/www/vhosts/example.com/httpdocs/uploads/ for data storage, but the installer says:

Your data directory /var/www/vhosts/example.com/httpdocs/ must be outside of your install path.

How can I do this? Folders outsute httpdocs were not writeable :(