okay, I've tried several times to get thru the advanced construction tutorial. Each time I get to the abort action group and it won't ungrey. I've looked at the youtube link above, though it is from an earlier version of KSP. They did exactly what I did (sigh, including the errors). However, his button lit up and my still stay grey. I have set up the decoupler under the pod and the two radials. Further, as the tutorial instructs, I've shut down both liquid engines (to no avail). I have even tried shutting down the two boosters. Nothing is working. I have even restarted the tutorial several times and waited a few days in between restarts. HELP!!!!!
Okay, I fortunately downloaded the game from Steam. After almost a week of frustration I decided to validate my files and discovered that indeed some files needed fixing. Now the next button works. Hope this helps someone to resolve this issue as well.
