I used to have the same problem with my ctx700 dct. Purchase the bike without working gears. It wouldnt go to D with check engine light+abs light on. After doing self diagnostic with the service manual it leads to fault in the PCM. Took the bike to Honda dealer so they can run their diagnostic tool and confirmed its the PCM fault. I've got tempted to get used PCM from US (100$) despite the different serial number and naturally it didnt work. Then finally got used Euro PCM + HISS + all locks and keys for 450Euro and gears worked first time with all warning lights off. The bike was 3yo with 9000km. I even called Honda Italy where the bike was originally purchased and they told me that they have replaced the PCM already at 5000km under waranty. So as it turns out not reliable peace of engineering.
Doing self diagnostic with the SM can tell you if its the shift control motor, or any of the solenoids, side stand etc.
Oh! Something else I've discovere is that I could still used the non-HISS ECU that I initially bought, what I've only needed to do is to feed 12V to the only empty pin on the plug I didnt notice it at first as they are a lot of wires like 50 or 60. That empty pin 'tells' the ECU that the HISS is 'okay to go' or this way you simply bypass it and wont have HISS anymore but hey its 6 times less expensive ECU.
Troubles with that DCT module made me give up on auto boxes, but its such nice having auto, next bike I bought is a 1200D now with granaded engine. I'm also so close to give up on everything. I need to spend 1/3 of what I've paid for the bike to get used engine, probably only to get faulty PCM later. Its a fantastic bike, but seriously unreliable.