I am using Micro.
I have tested the PCB board with multimeter. No problem there.
To make sure the problem is not on the PCB. I also unplugged the GPS only from the PCB and connect it with wire so that I could exchange the order of TX and RX and change back to SoftwareSerial(8, 7).
And I even tested my old board(which I set up all the wires).
So the problem can only be that SoftwareSerial(7, 8) does not work.
Did any one meet such problems?