WPMU 2.8.4a won't install

[hlr]

After many, many attempts to upgrade WPMU and previous attempts to install WPMU2.8 I lost all data and started over again.
I downloaded 2.8.4a, unzipped and published.

1. The docs say that the install directory has to be 777. Not true: I get a server error if I do so.

Run index.php > server error
Run index-install.php > data are asked (DB name, DB user, DB pw)
afterwards 404 file not found

Edit wp-config-sample.php with the DB data, and publish as wp-config.php
index.php says Database Tables Missing.

Quite obvious: yes, this is a new installation, so there are no data in the DB.

[dd32]

Please direct all MU-related items to the WordPress MU tracker: ​http://trac.mu.wordpress.org/

However, You may be better off in the MU forums: ​http://mu.wordpress.org/forums/