Well--first question is "did you follow the instructions"?
Could be several things.
Yes, the connector can be too flat to the housing. It should spring
out at a bit of an angle. Put the stock one in, look at the angle. If the
new one is flatter, bend it. It's not that tough---you can do it be hand.
Bending it a little too far won't cause too much grief---it will just rub the
little ear a bit harder against the slide.
Trigger spring. Can be install incorrectly, usually it will drag on the housing
and not allow the trigger to "pop up" and reset when the bump on the inside
of the slide pushes the connector out of the way.
The best way to diagnose Glock trigger problems: Get a cut down slide
cover plate (the thingy that slides into the rear of the slide and retains
the striker and extractor springs). They make a orange one called an
armorers plate, or you can just grind off the lower third or so of a stock one.
With STOCK parts and a good light, cycle the gun and watch how the parts
interact. Put in the aftermarket parts. See any difference in how the
parts make nice with each other? If you do---that's probably the problem.