Silly question, but is the "www.trees.somedomain.com" virtual the same one that handles "www.outdorr.somedomain.com"? The reason I ask is to make sure that the pool of servers that is currently targeted from
"www.trees.subdomain.com" will get the request and need to be able to handle the other domain. If you have different pools for the two domains, then you'll likely need to assign the traffic to that pool from within the iRule with the "pool" command.
If they are both configured under the same pool of servers, then can you look at the web server logs and see what the request is going in as to make sure the changes are taking hold?
-Joe
Nimbostratus