[rules-users] Implement timer in rule

Hi All, I am trying to implement a timer in a rule so that it executes every 15min i have the following code: rule " When average temperature is greater than 19 turn on fans" timer(int:0 15m) when $t : Temperature($room : room) $fan : Fan( room == $room ) then "i need to implement this yet end I am getting on the timer: "[ERR 101]Line 61:0 no viable alternative at input 'timer' in rule ...... I read example 2.12. Example timer attribute uses from https://hudson.jboss.org/hudson/job/drools/lastSuccessfulBuild/artifact/t... and this is how it says to implement a timer. Any help is greatly appreciated. Kind regards, James.