Nginx redirect to PhantomJS

I am attempting to redirect to a phantomJS instance running on port 8888. However it is failing. The regular page loads, but when I change the #! for the ?_escaped_fragment_= it just gives me the regular page still...

Excerpt from the nginx file

user www-data;
worker_processes 4;
pid /var/run/nginx.pid;

events {
        worker_connections 768;
        # multi_accept on;
}

http {
        if ($args ~ _escaped_fragment_) {
                proxy_pass http://localhost:8000/?_escaped_fragment_=/;
        }

        #mi angular app
        server {
        location / {

                root /var/www/html/miwebapp/client/app;

        }
        }

        ##
        # Basic Settings
        ##

        sendfile on;
        tcp_nopush on;