NFS exportfs -a fails

I am running Volumio on my RasPi and I want to export the internal storage directory (/data/INTERNAL) so that anyone may mount it to add/remove music. When I run 'exportfs -a' I get the following message:

exportfs: /data/INTERNAL does not support NFS export

I was running into this issue trying to export from my encrypted /home/folder on my Ubuntu machine however Volumio doesnt use encryption (to my knowledge).

Interestingly, when I run 'showmount -e 10.0.1.21' (server-ip) from the from the client (Ubuntu 14.04) it returns the following:

Export list for 10.0.1.21: /data/INTERNAL 10.0.1.1/24

I thought perhaps this was just a bug so when I went to mount from the client with 'sudo mount 10.0.1.21:/data/INTERNAL /nfs' it returns this:

mount.nfs: access denied by server while mounting 10.0.1.21:/data/INTERNAL

(note: I have also tried mounting with 'sudo mount -t nfs -o proto=tcp,port=2049 10.0.1.21:/data/INTERNAL /nfs' and 'sudo mount -o v3 10.0.1.21:/data/INTERNAL /nfs' each with the same output)

I have set /data/ permissions recursively to 777 and here is my /etc/exports output:

# /etc/exports: the access control list for filesystems which may be exported
#       to NFS clients.  See exports(5).
#
# Example for NFSv2 and NFSv3:
.
.
.
# Example for NFSv4:
# /srv/nfs4        gss/krb5i(rw,sync,fsid=0,crossmnt,no_subtree_check)
# /srv/nfs4/homes  gss/krb5i(rw,sync,no_subtree_check)
#
/data/INTERNAL 10.0.1.1/24(rw,fsid=0,no_root_squash,sync,no_subtree_check)

Im pulling my hair out over this one.