First I installed a Fan in my living/dining room, then I installed a chandelier from another ceiling outlet... all good and every thing works just fine. However, some time later I discovered that my power drill would not work on the balcony GFCI outlet. The tester indicates "Open neutral." One circuit breaker controls all three plus a balcony light. Everything on this circuit works except the GFCI outlet, which is the furthest of all from the breaker box. The GFCI tests ok. Any ideas? Many thanks in advance.