w3 Total Cache activation errors

Trying to install W3 total cache. I am using wordpress in a network multi site format.

I’ve chmoded the wp-content directory to 777

Uploaded the plugin.

When I go into one of the sites and try to activate it I get an error that says I need to add

define(‘WP_CACHE’, true); before require_once(ABSPATH . ‘wp-settings.php’);

to my wp-config file.

I’ve done this and when I go to reactivate the plugin I get the following.

Parse error: syntax error, unexpected T_REQUIRE_ONCE in /home/vmps/public_html/wp-config.php on line 108

this is where I placed the code supplied. This basically kills my site until I remove the code from wp-config.

Any ideas on how I can resolve this?

thanks,

Bill