[Laird Scooby]

At the risk of sounding patronising, you haven't fitted the LED the wrong way round have you?

Other things to check are for very tiny "hairs" of solder where they shouldn't be, for example between tracks on the board, the pins on the plug etc and for any broken or incorrectly connected wires. A common mistake when connecting to a multiplug from a diagram is to connect the wires as viewed from the "plug" side, not as they should be from the "wire" side. When i say common, a neighbour renewed the 7-pin trailer plug on his trailer recently and couldn't understand why it wasn't working correctly. Didn't take long to sort out for him but his head was red-raw from scratching!