I took the trap apart, no clog. I think there is a clog in the Trap arm. This is behind a cabinet wall. I have tried to snake it, but unsuccessful. Help Please!

Hi Fvhole and welcome to the Plumbing Page at AMHD. You are correct, The clog's in the drain line in the wall. The solution would be to remove the traps "J" bend and send a snake up into the wall,(see image). There's a bend ablout 8 inches in but once around that you only have to put out 6 more feet of snake. Flush with a tub of hot water. Good luck and thank you for ratting my answer. Tom