As long as the sockets are wired in series and not in parallel and that you broke off the taps connecting the two sockets on the outlet, you should be good do go, you could test it by carefully shorting the socket (the one without the bulb) and the bulb should light up, full brightness. Before you do that, confirm that the bulb is know good (another good use for your meter) but you already checked it in another fixture. If you short it and the bulb does not light up but you blow a fuse (or throw a circuit breaker), then it’s not wired correctly. The bulb must be in one of the sockets to complete the circuit. As I mentioned previously, depending the current draw when you switch on the amp, the bulb may not light up at all.