htaccess ErrorDocument being ignored.

'Lo there

I have a pretty simple .htaccess on one site hosted on a v'min server, but it is rather bamboozling as to why it doesn't work;

ErrorDocument 403 /403.html

Order deny,allow
Deny from all

The Limit Post works fine - that generates 403 errors. the 403 page exists, but instead of redirecting there, it goes to the CentrOS Apache 2 Test Page instead. I've dug around in V'min and found: Services-->Configure Website --> Error Handling, and set the 403 to the url. Also no result.

Any idea what is overriding it?