How to find nvl table?

[Bobo <boboaq@xxxxxxx>]

HI

     Some days ago ,a member of here reply me the followings about traffic account:
>try this one:
>
>iptables -nvL INPUT
>
>in Perl:
>
>open(CHAINS, "iptables -nvL INPUT|") or die "Error reading chains\n";
>
>while(<CHAINS>)
>{
># read the lines one by one, matching on the text you want
>}
>
>close(CHAINS);

   My platform is Redhat 7.2 in  default congiguration.

  While I execute "iptables  -nvL input"

  I got the following message on screen:


   [root@xxxxxxxxxx account]# iptables -nvL  input
iptables: Table does not exist (do you need to insmod?)

    why?  how to find the talbe? does  it need a special patch?

 Thanks.