2 Switches + 2 Light Fixtures = a problem that needs help!
You are trying to feed your new light from a switch loop and as you've found out, it doesn't work. You have your source, hot and neutral, going to the hanging lamp. There, the neutral is tied to the lamp.The 12/2 going to the junction box and to the switch box is the always hot, probably the white, and the switched hot, probably black. That's what you spliced into, there is no neutral and you need one. One solution is to run a 12/2 source, hot and neutral,from the lamp to the light, hook your neutral to the lamp and then run your switch loop to the switch box. Disconnect the wire you ran from the junction box to switch 2. When running a switch loop, the always hot is supposed to be the white wire and it should be marked with some black tape to differentiate it from a neutral wire.