Problem configuration de openvpn sous debian8

root@vps77389:/etc/openvpn# systemctl status openvpn@server.service
● openvpn@server.service - OpenVPN connection to server
   Loaded: loaded (/lib/systemd/system/openvpn@.service; disabled)
   Active: failed (Result: exit-code) since Tue 2016-04-19 08:24:50 EDT; 19s ago
  Process: 1314 ExecStart=/usr/sbin/openvpn --daemon ovpn-%i --status /run/openv                                                                             pn/%i.status 10 --cd /etc/openvpn --config /etc/openvpn/%i.conf (code=exited, st                                                                             atus=1/FAILURE)

Apr 19 08:24:50 vps77389.vps.ovh.ca ovpn-server[1314]: Options error: --dh fa...
Apr 19 08:24:50 vps77389.vps.ovh.ca systemd[1]: openvpn@server.service: cont...1
Apr 19 08:24:50 vps77389.vps.ovh.ca systemd[1]: Failed to start OpenVPN conn....
Apr 19 08:24:50 vps77389.vps.ovh.ca systemd[1]: Unit openvpn@server.service ....
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