Adding new IP address to ISPConfig

So I have put the new IP address into the server settings of ISPConfig, but it dosen't seem to be active. I can't ping it nor does it show up with ifconfig. What do I need to do to Ubuntu (7.04) to get the new IP online?

Code:

eth0      Link encap:Ethernet  HWaddr 00:50:56:11:22:33
          inet addr:24.121.65.131  Bcast:24.121.65.255  Mask:255.255.254.0
          inet6 addr: fe80::250:56ff:fe85:7799/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:155704 errors:2 dropped:2 overruns:0 frame:0
          TX packets:7578 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:32921186 (31.3 MiB)  TX bytes:7507036 (7.1 MiB)
          Interrupt:17 Base address:0x1400

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:211 errors:0 dropped:0 overruns:0 frame:0
          TX packets:211 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:112660 (110.0 KiB)  TX bytes:112660 (110.0 KiB)