Hi I replaced a Flash immersion timer with an apt one today and it seemed straightforward but just wondering should the light on isolation switch not always stay on even when the immersion switch is set to off.Also when I flick the switch on the isolation to off and leave the immersion at on the light on the immersion stays on!Is this normal as I thought when I turned off tge isolation switch it wouldn't allow the immersion light to come on?Is it wired correctly?