iRule to return URL/URI doesn't log anything?

I am just getting started with iRules.

We have an Atlassian JIRA suite that runs both Service Desk & JIRA Software. We want to configure an iRule that will allow us to use a different URL for Service Desk requests, which will allow us to re-use our already existing Helpdesk URL.

Being new to iRules, I'm just trying to get a feel for how they work and what the various HTTP::uri, HTTP::host, HTTP::path options are being seen as on the F5.

when HTTP_REQUEST {

  log local0. "URI = [HTTP::uri]"

log local0. "URL = [HTTP::path]"

log local0. "Host = [HTTP::host]"

}

When I create this iRule and apply it to my Virtual Server, I get no logging that indicates that this iRule is being hit. There are other iRules that have other functions (not only set to log) that use similar logging arguments that work fine.

What gives?