Mounting Popcorn Hour NFS share on B3

I use a Syabas Network Media Tank (Popcorn Hour), which comes with a built-in NFS server.
I also use NFS on other computers in my network, so I have installed the package nfs-kernel-server on my Bubbas:

apt-get install nfs-kernel-server

On the Bubba and Bubba2 I had the NFS share on the Popcorn Hour mounted by having an entry for it in /etc/fstab:

popcorn:/opt/sybhttpd/localhost.drives/HARD_DISK/Video /home/storage/mounts/popcorn nfs user,rw,async 0 1

This has worked fine, but when I tried to mount the same NFS share on B3 I got Permission Denied errors.
After a lot of time troubleshooting I found that the problem was not the permissions in /etc/exports on the Popcorn Hour, nor a network issue, but the version number mount.nfs on B3 sends to Popcorn hour in the mount request.

The solution is to add "vers=3" to the options in /etc/fstab:

popcorn:/opt/sybhttpd/localhost.drives/HARD_DISK/Video /home/storage/mounts/popcorn nfs vers=3,user,rw,async 0 1

I hope this might save someone else the time it took me to get this working :-)