Trying to connect AD server backend via HAPROXY: getting "Layer6 invalid response, info: "SSL handshake failure""

Problem

1. have ha-proxy on Ubuntu server
2. Then one Ad server on backend

Error I am getting is

erver adserver/ad-1 is DOWN, reason: Layer6 invalid response, info: "SSL handshake failure", check duration: 1ms. 0 active and 0 backup servers left. 0 sessions activ… remaining in queue.

Config file

            frontend lb
               bind 0.0.0.0:389 ssl crt /etc/ssl/private/haproxy-lb.key
               default_backend adserver
            backend adserver
               balance roundrobin
               cookie JSESSIONID prefix nocache
               server ad-1 x.x.x.x:389 ssl verify none check cookie ad-1

Any thoughts on this?