Use a good wirenut, do not "fold" any wires back. When joining stranded to
solid wire, leave the stranded wire about 1/16 longer than the solid, and
twist the wirenut on firmly. pull on the individual wires to make sure they
are connected well. Do not just shove the ground wires thru a knockout.
wirenut them to the ground wire in the fixture, or run a pigtail to the
grounding screw. you want to make sure that the ground wires are secured
well.