Not going so well

The potty training is not going well at all!! I dont know what Im doing wrong! We've tried offering candy, toys, anything just to get Logan to even sit on the potty. He screams when I put him on it. I dont know if he is scared about something or what but I cant understand it. He use to tell me when he needed to go pee but now he wont even do that. I've tried using the timer and taking him every 20 minutes, but nothing ever comes out and as soon as I take him off the pot he peeps on the floor. Same results when I put him in "Big Boy" underwear. NOT Pull Ups. He runs around having fun then will just pee on the carpet. We live in an appartment and Im getting tired of all the cleaning. Nothing seems to be working with this kid. UGGGGG!