Temps dip below 50F. Perhaps low humidity. Missouri Botanical Garden says seldom sets fruit indoors. Several posts on Garden Web (2006 thru 2013) from folks who say they're successful live in central Florida.

I found that happened with my first flowers. You probably got an older plant that was just reaching fruiting stage. Not that unusual for them to abort. Next year will probably be better. They do like a highly organic medium, they burn fairly quickly with chemical fertilisers.

I always reuse my potting mix and this year I have passion vines coming up in everything. You see an empty pot sitting around for months and figure there's nothing in it.....wrong. lol I know loads of folks that like okra. I'm just not one of them. The slimy texture gets me every time. Piper nigrum is pretty easy to root. I don't have any now but you might want to post on the exchange and see if anyone can send you some.

I don't (yet) have specific experience with piper nigrum, but my ginger and turmeric and super dwarf banana plants thrive under the red-blue (mostly red) led grow lights. I've tried Phillips Agro lights (incandescent reflector 'flood' lights), various T8 and T5 "grow lights" and I haven't found any that my plants (especially the tropicals) really thrive under. They sometimes do OK if the bulb is really close to the plants, but if you have the light what looks like 'normal' distance above the plants, all my plants seem starved for light with the fluorescent or incandescent lamps. You can find the LED light bulb units online for $20-$25 or so. Look for E26 base or 'medium base,' so they fit a standard light socket. I use those bulbs in the clamp on light sockets you get at home depot for $8 or so for work lights, or some old (antique) floor standing "reading lamps" I got at the thrift store. I've had great results with PAR 38 size LED units from ABI lighting (12W and 18W) and Apollo Horticulture (claims 24W, but actually closer to 15W), and I've heard good things about Taotronics. If nobody is looking at the things, all of those bulbs are great for the plants. Plants don't care if the light is "funny looking" to humans. If it's where people see it, you might want one like the ABI 18w unit, with some white in the mix. Those are (slightly) less 'funny looking' to people. My plants don't care, but for the one I have in the living room on display, I use the bulb with the white in the mix. I'm about to try starting some piper nigrum from seed (I couldn't find cuttings at a reasonable price), and I'll be using one of my LED grow lamps (on a programmable timer set for sunrise and sunset times for 23.5 degrees north latitude) , a heating pad under the seed starting pots initially. From what I've been told, Piper nigrum needs warmth (temps over 70F are ideal, under 65F can be harmful), and also needs high humidity. My tropicals spend the winter in a heated area that also has a hot-plate with simmering water on it (refilled daily).