permissions on a USB drive are not changing even after all tricks need to use it on nfs

[Tapas Mishra]

Ok here is some tricky situation not too sure as to what is causing problem.
I shared a partition on a USB using NFS to some poor server which can
use this as a backup hard disk.
The problem I have with this USB hard disk is
I see it mounted in /media (which I do not have to do)
permissions I see are
drwx------  1 tapas tapas 16384 2010-10-05 14:39 some_arbit_directory_in_media
when on the client machine I run

mount -t nfs4 -o proto=tcp,port=2049 <Ip of Tapas NFS>:/media/myshare /mnt/nfs/
I get following error

mount.nfs4: mount system call failed

to me it seems since /media/myshare on my nfs share does not have
write or read permission
so might be nfs daemon is not able to read it.
So I changed the permissions
chmod 777 -R /media/myshare   (I deliberately want 777)

but then there was no change in the permissions of the mounted partition of USB
when I do an ls -l /media to see if the permissions changed I see

drwx------  1 tapas tapas 16384 2010-10-05 14:39 /media/myshare

there is no effect of chmod here.

On the other hand the client machine which is supposed to mount it is
failing to do so.

mount -t nfs4 -o proto=tcp,port=2049 <Ip of Tapas NFS>:/media/myshare /mnt/nfs/
mount.nfs4: mount system call failed

What more should I be looking ?