I have a range of servers with a sensor that calls a perl script. The result is then shown in PRTG, and that part works (it's a script for showing status of Postfix queues).
I've then created a factory sensor that sums up all these sensor results. For some reason the sensor shows old values, ie. if I've forced a refresh of the underlying sensors, the factory sensor is not reflecting the new values (not even after that is refreshed).