[HyperDB] Invalid argument supplied for foreach() in db.php on line 638

[Tony Dillon]

Hello everybody,

I've run into a problem installing HyperDB in our production environment.
 The configuration is the same as on our development environment, so I'm
struggling to work out what's going wrong.

This is my "db-settings.php" config for the moment.  I've reduced it down to
bare minimum of one RW server for the moment while debugging.  Of course the
appropriate RW_DB_HOST variable has been defined.

*add_db_server('global', 0,    '', 1, 1,  RW_DB_HOST,    RW_DB_HOST,
    DB_NAME,     DB_USER,     DB_PASSWORD);*

As soon as I drop "db.php" into the wp-content folder the site stops working
with the following error appearing in the error logs.

*PHP Warning:  Invalid argument supplied for foreach() in
/var/www/vhosts/site/wordpress/wp-content/db.php on line 638*
*
*
At first glance this appears to indicate that there are no servers added for
the loop to enumerate, but that's about all I can tell.

Can anybody help?

Many thanks,
Tony