Win Server 2012 Failover Cluster - Error when adding disk onto a cluster (The error code was '0x1' ('Incorrect function.').)

Hi Techies

I'm currently running running 2 VMs Win Server 2012 and would like to test Failover Clustering for one of our FTP server

I've added on both servers an additional partition, formatted and Online, but cannot bring the disk online from the cluster manager

Assistance would be greatly appreciated

Thank you
Jabu