load balancing multi domanis error 500

Hi
I'm sorry for my english first!
So I have(for now, after more) 2 domains and 2 vps for nginx and 2 vps for mysql in loabalacing, when I put first domain everthing work fine with subdomain to.
2 vps with mysql and one of them use nginx as load balancing
2 vps with nginx for front-end web

Ok when I put new domain(xvideox.co) appaers error 500,but when i put xvideox.co/index.php the message is file not found, but have directory configurate right!....I dont know
I for dns server use cloudflare
With first(computereconomy.com) domain work fine.
Maybe is the proxy
This is my configuration back-end and front-end(just one vps):

http://computereconomy.com/files/nginx.conf-back-end.txt
http://computereconomy.com/files/back-end-default.txt
http://computereconomy.com/files/nginx.conf-front-end.txt
http://computereconomy.com/files/front-end-default.txt

I try alots for example:
ssi on;
name_server: _;
then
on bind
put master server with both domains Forward (Names to Addresses) and Reverse (Addresses to Names)
in all server and i try one server yes and one no and viceversa and both


Thank guy!!