ifconfig eth0:1 up, says - Cannot assign requested address

[Deboo <deboo@debian.elitemail.org>]

I am not able to set up ip aliasing on eth0.

Here's my eth0 configuration:

deboo@linux:~/$ ifconfig eth0
eth0      Link encap:Ethernet  HWaddr 00:50:8D:2C:0F:87
          inet addr:172.16.16.22  Bcast:172.16.255.255
          Mask:255.255.0.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1995806 errors:0 dropped:0 overruns:0 frame:1
          TX packets:76517 errors:0 dropped:0 overruns:0 carrier:0
          collisions:2293 txqueuelen:1000
          RX bytes:229267506 (218.6 MiB)  TX bytes:6883467 (6.5 MiB)
          Interrupt:9 Base address:0xdf00

deboo@linux:~/$
deboo@linux:~/$ ifconfig eth0:0
eth0:0    Link encap:Ethernet  HWaddr 00:50:8D:2C:0F:87
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:9 Base address:0xdf00

deboo@linux:~/$ sudo ifconfig eth0:0 up
SIOCSIFFLAGS: Cannot assign requested address

deboo@linux:~/$ cat /etc/network/interfaces
auto lo eth0

iface lo inet loopback

iface eth0 inet static
        address 172.16.16.22
        netmask 255.255.0.0
        broadcast 172.16.255.255
        gateway 172.16.1.1

iface eth0:1 inet static
        address 10.12.81.253
        netmask 255.0.0.0
        broadcast 10.255.255.255
        gateway 10.12.81.1


   A few days ago when I had put this same configuration and was able to
   up eth0:1 successfully without any problem. Now with the same
   config, it's giving this error. Where's the problem?

   Second, if you see the output of ifconfig eth0 above, there ar 2293
   collisions. What are these? Whatever (available) IP address I
   change to, I keep getting these collisions.

Any help appreciated.

Regards,
Deboo