Door locks
 

I have a 2000 Chevrolet Classic Crew Cab with power door locks. The locks work only on the first time you push the button then they won't work and all I hear is a clicking noise under the dash. I replaced the relay that is right above the brake pedal, but there is another box under the dash that clicks. Cna someone tell me what is wrong and how to fix it. I find it hard to belive that all 4 actuators are bad at the same time but I guess anything's possible. The Chevy parts man said it only showed one relay so I don't know what that other box that's clicking could be. Thanks. By the way it has keyless entry and a key fob.