Using HaProxy on Nginx server. Not listening to port 80.

Recently setup a server & using haproxy. Everything else runs smoothly but port 80 is not connecting. Here is the haproxy config file. Esp gives problem when certbot tries to renew. what am I missing here?

frontend backend.sample.com
        bind *:80

        # Test URI to see if its a letsencrypt request
        acl letsencrypt-acl path_beg /.well-known/acme-challenge/
        use_backend letsencrypt-backend if letsencrypt-acl
        bind 64.123.456.124:6684 ssl crt /etc/haproxy/certs/backend.sample.com.pem
        default_backend webapps

backend webapps
        balance roundrobin
        server app01 64.123.456.124:5684

backend letsencrypt-backend
   server letsencrypt 127.0.0.1:54321