Heartbeat ubuntu server 12.04 is not assigning virtual ip?

Heartbeat ubuntu server 12.04 is not assigning virtual ip?

I have two nfs servers and I have configured heartbeat on my both servers but when I started heartbeat it do not aign virtual ip to my servers
nfs-server-1 (eth0 172.16.203.20)
nfs-server-2 (eth0 172.16.203.21)
Virtual IP (172.16.203.23)
I configures /etc/heartbeat/ha.cf as follows on both servers same
logfacility local0 #used to tell heartbeat which log facility to utilize for logging
keepalive 2 #interval between heartbeat packets currently every 2 secs you could also use 2000ms
deadtime 5 # timeout before the other server takes over
ping 172.16.203.20 #address to ping to determine if we are alive
udpport 694 #port to listen in on for broadcasts made by heartbeat
bcast eth0 #device to use for broadcasts
baud 38400 #speed of serial device
serial /dev/ttyS0 #serial device to use
node nfs-server-1 # dns name of one of our two nodes
node nfs-server-2 # dns name of other of our two nodes
auto_failback on # very important or auto failover won't happen
And /etc/heartbeat/haresources as follows also same on both server
nfs-server-1  IPaddr::172.16.203.23/16/eth0 nfs-kernel-server
But when i test my servers ifconfig -a
eth0      Link encap:Ethernet  direcciónHW 08:00:27:3d:a1:fb 
          Direc. inet:172.16.203.20  Difus.:172.16.255.255  Másc:255.255.0.0
          Dirección inet6: fe80::a00:27ff:fe3d:a1fb/64 Alcance:Enlace
          ACTIVO DIFUSIÓN FUNCIONANDO MULTICAST  MTU:1500  Métrica:1
          Paquetes RX:18934 errores:0 perdidos:0 overruns:0 frame:0
          Paquetes TX:5581 errores:0 perdidos:0 overruns:0 carrier:0
          colisiones:0 long.colaTX:1000
          Bytes RX:3556847 (3.5 MB)  TX bytes:715714 (715.7 KB)

lo        Link encap:Bucle local 
          Direc. inet:127.0.0.1  Másc:255.0.0.0
          Dirección inet6: ::1/128 Alcance:Anfitrión
          ACTIVO BUCLE FUNCIONANDO  MTU:16436  Métrica:1
          Paquetes RX:54 errores:0 perdidos:0 overruns:0 frame:0
          Paquetes TX:54 errores:0 perdidos:0 overruns:0 carrier:0
          colisiones:0 long.colaTX:0
          Bytes RX:5304 (5.3 KB)  TX bytes:5304 (5.3 KB)
Whats wrong is with my configuration ?