Dell ME Series SAN - Cannot Add additional Hosts to group

Hi,

I'm in the process of commissioning an ME series SAN, and I'm attempting to add 3 iSCSI ESXi hosts to the SAN

I have successfully added the first host and in the process created a host group. On attempting to add the second host and adding it as a member of the host group, the configuration fails and I receive the following error message:

'The mappings of the host are inconsistent with the mappings of the host group. Therefore the host cannot be added to the host group'

Anyone got any idea why I am getting this error?

Thanks