[Closed] 160mm adapter fitting

Currently fitting some rs785 shifters/calipers, replacing a rival 1 setup. I've got a 160mm adapter for the rear (SM-MA-R160DDA), but a bit confused about the fitting. The adapter attaches to the caliper with those funny little pin-ended bolts, and here's where I got confused...
On the front, putting those in resulted in a satisfying "click" when in place...no such sound here, despite being torqued-up.

The instructions also seem to suggest using the same type of bolt (and some washers), to attach adapter to frame...but as far as I can see these are regular threads with no place for the pin to go. I assume I'm being a humpty somewhere but not quite seeing where atm...