Block part of website

Can you block part of a website say : www.mydomain.ie/testing/block but allow access to www.mydomain.ie or www.mydomain.ie/testing

Have created a custom list and tried blocking part of a website.  Within the test feature or websense it says that the category is custom and blocked, however in the logserver it comes up with Category = unknown and I think 1899.

Just to add - Have latest version of Triton working fine apart from this issue.......the custom filter does work for websites, just does not seem to work for webpages.

Thanks