I do 2 things different:
1 - /etc/exports
Code:
/exports/share 192.168.0.0/24(rw,async,insecure,all_squash,no_subtree_check,crossmnt,anonuid=1000,anongid=1000)
2 - manual mount of nfs share
Code:
mount 192.168.0.xxx:/exports/share /mnt/nfs
Then I point COPS to:
/mnt/nfs/books
Books is a directory inside /exports/share on the server.