Dumb wiring question

I'm the first to admit that I am quite electrical illiterate, so bare with me. I am trying to add some interior lighting in a boat. There is a factory toggle switch labeled 'courtesy lights' which turns on a small light fixture. I intended to just add wiring to this existing light fixture and run it to a few more places with some new low-voltage LED lights I bought. I bought a spool of 18/2 wire as suggested, planned out how to run the wiring, and where the new lights would go. Under the console I found where the wires ran from the toggle switch to a connection with the factory light. I simply unhooked those connections, added the new red wire to the red, and the new black wire to the other black wire. I only tried connecting the first light before going further with the rest of them - I have nothing. The factory light works but not the new one. I tested the new light with a 9v battery (as suggested) and it works. I've checked for a secure connection (multiple times). There must be something stupid I am missing. I've gone back out there 3 times and just cant figure it out. Any thoughts?