Neewer FC-16 and Nikon D5500

I have a Nikon D5500, SB-600 Speedlight and Neewer FC-16 wireless flash trigger and receiver system. My camera and flash are both in manual. The trigger and receiver are both set to “flash”. The green lights on them are flashing (so the batteries are fine). I still can’t get it to work. The speedlight doesn’t flash when I press the shutter on my camera! Is the Neewer even compatible with the D5500? Any suggestions?! Thank you! /Arvind