I am trying to mount from storage device to Linux machine over IPV6 IP.
Linux OS : RHEL5

The error message I get is,
[root@mindnic-06 ~]# mount -o tcp -t nfs 4444::2:/vol/vol2 /mnt/sridhar
mount: mount to NFS server '4444' failed: System Error: Invalid argument.

The same directroy gets mounted from IPV4 IP.

[root@mindnic-06 ~]# mount -o tcp -t nfs /mnt/sridhar

I have no idea what might be problem. Any pointers are welcome.
Thanks for your time,