CARP in FreeBSD10

[Efraín Déctor]

Hello.

I am triying to enable CARP on FreeBSD 10.0-RELEASE, I have read the 
documentation (http://www.freebsd.org/doc/en/books/handbook/carp.html) I 
tried to enable the module of carp, putting if_carp_load="YES" on 
/boot/loader.conf, rebooted and after that I tried to enable it using 
the command/ifconfig carp0 create/. However after that I get the 
following message:

"ifconfig: SIOCIFCREATE2: Invalid argument".

Then after that I rebuilded the kernel putting the option:

device    carp

But afther rebuilding and installing I still get the message "ifconfig: 
SIOCIFCREATE2: Invalid argument".

Can you guys point me in the right direction?. What am I doing wrong?.

Thank you very much