NFS ERROR: NFS Server Hostname failed:RPC Error: Program not registered

server I configured with NFS.
/etc/export file I add the entry what are directories need to mount
In the client /etc/fstab add the entry to mount  directory from server to client
IN THE CLIENT
While I try with #mount command To check what are things are mounted.
server shared directory it is not mounted to the client. So I try to remount
#mount -a it will mount directory according to the /etc/fstab file
while I try thes I got the following error message

mount: mount to NFS server '128.150.72.58' failed: RPC Error: Program not registered

I check in the server whether rpc support nfs. Because rpc - Remote Procedure Call is required share nfs File System.
TROUBLESHOOTING ISSUE
1)rpcinfo -p
[root@master1 ~]# rpcinfo -p [ it will show portnumber what are thing related to rpc]
program vers proto port
100000 2 tcp 111 portmapper
100000 2 udp 111 portmapper
100024 1 udp 1006 status
100024 1 tcp 1009 status
100011 1 udp 739 rquotad
100011 2 udp 739 rquotad
100011 1 tcp 742 rquotad
100011 2 tcp 742 rquotad
100021 1 udp 54266 nlockmgr
100021 3 udp 54266 nlockmgr
100021 4 udp 54266 nlockmgr
100021 1 tcp 58009 nlockmgr
100021 3 tcp 58009 nlockmgr
100021 4 tcp 58009 nlockmgr
100005 1 udp 813 mountd
100005 1 tcp 816 mountd
100005 2 udp 813 mountd
100005 2 tcp 816 mountd
100005 3 udp 813 mountd
100005 3 tcp 816 mountd
From these troubleshooting I found NFS it is not associated with RPC.
SOLUTION
So,I restart the NFS service.
In the first time NFS is not shutdown properly.
so, I restart it again. then I try it
[root@master1 ~]# rpcinfo -p | grep nfs
100003 2 udp 2049 nfs
100003 3 udp 2049 nfs
100003 4 udp 2049 nfs
100003 2 tcp 2049 nfs
100003 3 tcp 2049 nfs
100003 4 tcp 2049 nfs
So Here I confirm RPC Provide service to nfs.
Then in the client again I try to remount it with mount -a option.
it is mounted perfectly with out any issue.Then the problem has been clearled.
Mount to NFS Server Hostname failed:RPC Error: Program not registered.