ip-adress problem proxmox 2.3

Hi!

A few days ago I installed proxmox 2.3 on my server. I entered an unused ip-adress in the installation.. But now it refuses to connect, nothing works.

The firewall havent registered that any proxmox client is connected, I just see my computer and my other servers. (im running pfsense)
I cant ping my firewall from proxmox, and I know that the cable and the port in the switch works, ive used it before.

So now im running ubuntu temporary (and it works), but I really need to get proxmox to work.

I changed ip in /etc/networks/interfaces (if I remember the path correct)
And then issued the command /etc/init.d/networking restart

But that doesnt do any difference, Still no connection.

Why is there no dhcp in proxmox? That would be great..

Thanks
Krazos