reverse/backup lights not working

I already checked the backup light switch on the transmission and there's continuity when gear is in reverse. I provided battery power to the wires that lead to the reverse lights and both bulbs turn on. But when the two sets of wires are connected, I get nothing. I also just replaced the switch a year ago. From what I've read online, it's a pretty simple switch. I bought a new switch (JA4194) but I don't want to open it unless I'm sure is the switch. What else can I check? It's a 97 Protege LX manual transmission.

Thanks in advance.