Can not access to IP defined during installation

[Guest]

[smalldragoon]

Hi,
Being just a newbie user, I installed the soft on a blade Server.
everything went fine ( I needed to do a CRTL+C during install of packages for spamAssassin at it seems to block forever the install )

Now everything is installed, and I defined an IP address as requested.
when I check the links ( show network links ) , I can see 6 links
1: lo
2 : eth0
3 : eth1
4 : eth2
5 : eth3
6 :br0

When I check the addresses ( show network addresses ) ,
lo : 127.0.0.1, fine
1: lo
2 : eth0   ( link on this card, no prob )
3 : eth1 ( link on this card, no prob )
4 : eth2
5 : eth3
6 :br0 ( "link" and ip define : 10.200.0.254/16)

but can not ping and of course access to the GUI
what am I missing ? anything to activate ?
Thx