onSessionEnd actually doing anything?!

i want to do something very simple: when session expires, automatically redirect to a login page.

onSessionEnd looks like the logical choice, but i wasn't able to make it do anything at all!

any example that can show this function can do stuff is welcome, i've tried a bunch of them already, nothing works.

<cfcomponent output="false">

    <cfset this.name="testApp" />

    <cfset this.sessionManagement = true />

    <cfset this.applicationTimeOut = CreateTimeSpan(0,0,0,20) />

    <cfset this.sessionTimeout = createTimeSpan(0,0,0,20) />

    <cfset this.clientManagement = true />

    <cffunction name="onSessionEnd" access="public" returntype="void" output="false">

        <cflocation url="login.cfm">

    </cffunction>

</cfcomponent>