"cannot bind socket"

[Anthony CHEREL]

Hi,

I tried to make a small redirection using ACLs, but when i restart 
haproxy, debian display me this message :

starting frontend rules : cannot bind socket
failed !

backend webfarm 192.168.0.99
               balance roundrobin
               option redispatch
               cookie JSESSION prefix
               option httpclose
               option forwardfor
               option httpchk HEAD /check.txt
               server webA 192.168.0.102
               server webB 192.168.0.103
               stats auth admin:admin
               stats enable

frontend rules :80
            acl redir_web hdr_end(host) -i www.web.com
            use_backend webfarm if redir_web



what did i forget ?