Have you tried using it in the mu-plugins folders or network activating?
Which version of WP are you using?
If you try network activating it tells you it cannot be activated network wide. I am using wordpress 3.0.1. I have not tried the mu-plugins folder, but not sure why I would need to. I will look into that as a possibility though.
I am also experiencing this problem, but I am using W3 Total Cache on WPMU 2.7 in a subdomain blog using WP Subdomains to create virtual subdomains for pages on my subdomain blog in the root namespace alongside the WPMU subdomains. I hacked the core to accomplish this — wpmu-settings.php to be specific. However, I would still like W3 Total Cache to work on these subdomains:
about.thripp.com
contact.thripp.com
domains.thripp.com
index.thripp.com
gallery.thripp.com
portfolio.thripp.com
portraits.thripp.com
As you can see from looking at the HTML source, the W3 Total Cache HTML comment is being inserted at the end but it isn’t optimizing the page at all. Compare to the source code of my home page, richardxthripp.thripp.com, which is minified, gzipped, and fully cached.
there are a couple of threads around where the plugin authro says its not fully implemented – meaning multisite functionality.
a couple of other users have found a workaround by deleting the object.cache file…
check the other thread for this plugin too!
Any links to those threads?
I have a WP 3.0.1 network installation, the plugin works perfectly on the main site but not on the sub sites.
Also, if I try to disable CDN or Object Cache in the admin the “Deselect this option to disable all caching functionality.” checkbox will also be disabled, if I enable it it will also enable the disabled checkbox, for example the CDN.
Any clues how I can get this to work on my sub sites?
Seconded, I also want to know how to cache subdomains, external domains, and subdomains implemented through unorthodox means.
Sorry, I totally misinterpreted the “Deselect this option to disable all caching functionality.” checkbox…