IPv6 bind fails with 49 (#define EADDRNOTAVAIL 49 /* Can't assign requested address */)

I have a ipv6 interface(ping6 to a remove ipv6 works) when I try to bind to this address through a socket program "sobind" fails with "49" as return value. If I give "saddr6.sin6_addr =  in6addr_any;" sobind works.

Any idea what could be going wrong here? 

roundhay# ifconfig cxgbe1
cxgbe1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=6c07bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,TSO6,LRO,VLAN_HWTSO,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
        ether 00:07:43:11:89:88
        inet6 2010::102 prefixlen 64
        inet6 fe80::207:43ff:fe11:8988%cxgbe1 prefixlen 64 scopeid 0xd
        nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
        media: Ethernet 10Gbase-SR <full-duplex>
        status: active
roundhay# ping6 2010::101
PING6(56=40+8+8 bytes) 2010::102 --> 2010::101
16 bytes from 2010::101, icmp_seq=0 hlim=64 time=0.950 ms
16 bytes from 2010::101, icmp_seq=1 hlim=64 time=0.158 ms
^C
--- 2010::101 ping6 statistics ---
2 packets transmitted, 2 packets received, 0.0% packet loss
round-trip min/avg/max/std-dev = 0.158/0.554/0.950/0.396 ms



Code:
=====
{
            rv = socreate(AF_INET6, &sock, SOCK_STREAM, IPPROTO_TCP,
                                td->td_ucred, td);

                if (rv != 0) {
                        os_log_error("sock create ipv6 %s failed %d.\n",
                                        tbuf, rv);
                        return NULL;
                }

                family = saddr6.sin6_family = AF_INET6;
    inet_pton(AF_INET6, "2010::102", &saddr6.sin6_addr);
                saddr6.sin6_port = htons(ep->port);
                saddr6.sin6_len = sizeof(struct sockaddr_in6);

                rv = sobind(sock, (struct sockaddr *)&saddr6, td);
}


Here is the code snippet from where EADDRNOTAVAIL  is returned.

File : netinet6/in6_pcb.c

in6_pcbbind(register struct inpcb *inp, struct sockaddr *nam,
    struct ucred *cred)
{
……..
……..

} else if (!IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr)) {
                        struct ifaddr *ifa;

                        sin6->sin6_port = 0;            /* yech... */
                        if ((ifa = ifa_ifwithaddr((struct sockaddr *)sin6)) ==
                            NULL &&
                            (inp->inp_flags & INP_BINDANY) == 0) {
                                return (EADDRNOTAVAIL);  it fails here since ifa_ifwithaddr() returns NULL
                        }
……..
……..

}

File: net/if.c
struct ifaddr *
ifa_ifwithaddr(struct sockaddr *addr)
{

        return (ifa_ifwithaddr_internal(addr, 1));
}

ifa_ifwithaddr_internal(struct sockaddr *addr, int getref)
{
……..
……..

TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
                IF_ADDR_RLOCK(ifp);
                printf("ifp->xname:%s ifp->dname:%s\n",ifp->if_xname, ifp->if_dname);
                TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                        if (ifa->ifa_addr->sa_family != addr->sa_family)   ifa->ifa_addr->sa_family=18 & addr->sa_family=28. Even though the interface is in IPV6 mode its sa_family is not  set properly, 
                                                        continue;
}
Ifa = NULL;
……..
……..

}