Cannot create file share on 2-node 2012 file server cluster

I'm basically following this guide: http://derek858.blogspot.com.au/2012/10/windows-server-2012-smb-transparent.html but I am not using RDM disks, rather just standard vmdks running on vmfs. I can successfully create the cluster and everything looks like its running.

When I go to add a file share using the fail-ocer cluster manager, I only get the option to specify a custom path, I cannot select 'by volume' and no volume is listed. When I enter in a custom path I get an error - "the entered path is not valid for the selected server. Please enter a new path or select a different server".

Any ideas?