The chip that was in backwards sends the zero cross signal to the PIC and without this signal, the PIC will not know when to switch on the lights and will do nothing. It is possible that this chip may have been damaged when it was put in backwards. If you have another LE kit, I would try the chip from that kit (put in correctly) and see what happens. The fact that it is working in test mode and is lighting the signal LED shows that it is receiving the signal and the PIC and Triacs are working properly. The PIC just doesn't know when to switch on the Triacs.