Another Indicators question

Right (i've searched the forum by the way) i've fitted another pair of Oxford Mercury indicators on the back of my 07 SD as it had a tail lights with integrated flashers before. Not the perplexing thing is, they flash perfectly ok (as i expected) as i've only changed the style of indicator, they've always been LED, but the indicator light on the dash just stays on, i'd have thought it was the same circuit but it would appear not