using the igmph structure with skb : error in value

Hi,

I work on a kernel 2.6.21 with ebtables.

I develop a module for ebtables, and I need to analyse the igmp header.

I have this function (just to see the value)

static int ebt_target (struct sk_buff           **pskb,
                        unsigned int             hooknr,
                        const struct net_device  *in,
                        const struct net_device  *out,
                        const void               *data,
                        unsigned int             datalen)

{
struct sk_buff          *skb = *pskb;
printk ("igmp type :%u\n", skb->h.igmph->type);

}

I send a igmp packet to join a group
and I recieve this

       igmp type : 70

Normaly the good value in my case is  22 (I worked with igmp v3).

I don't undestand the response?

Then I try to see the ip of the multicast group (I send for the group
239.255.1.4) , I recieve 0.0.24.0 .

It's really strange because if I try to see the ip address of the
packet, it's works  (skb->h.ipiph->daddr) : 224.0.0.22