"NF_IP_PRE_ROUTING" macro not found
I am writing a netfilter module. In my module I included both netfilter.h and netfilter_ipv4.h. But when I am assigning NF_IP_PRE_ROUTING macro to hooknum field of nf_hook_ops struct it is showing me error saying that the macro is not declared. But according to source tree it is supposed to be declared in netfilter_ipv4.h. Can anybody tell me why it is happening and what is the solution of this problem?
N. B.: I am using CentOS 6.0. Kernel release 2.6.32-71.el6.i686.