More info required, you are using TB811 on CI810 FCI or on TB815, In case of CI810 what is status of other LED ? I hope it is running(R-green), no fault (F- LED off), valid +5v dc (P-green), T1 & T2 yellow blinking. Check inserted image here
If your optical cable connector is duplex than there is no possibility of wrong cable connection as there is latch. But if it is simplex than For simplex cables by convention, the gray connector is the transmitter end and the blue connector is the receiver end.
I hope your address setting on FCI modules are valid, I have never used advant and optical module bus interface, but trying to help you out with available information……