1. Assuming this is your mount command

mount -t nfs -o vers=3 XXX.XXX.XXX.XXX:/myserver/nfs /myclient/nfs

2. And if you are using showmount command from an NFS client and the following are observed

clnt_create: RPC: Program not registered

3. You have to access the NetApp Storage to check the NFS Protocol is enabled. I’m using the Netapp OnCommand System Manager

4. Check that the NFS Client can mount.

showmount --no-headers -e nfs_server
/ (everyone)

References:

1. showmount fails with clnt_create: RPC: Program not registered when executed from a RHEL6 NFS client communicating with a NetApp filer