Adding a second HDD to PBS

Hi all,

I want ot add a second HDD to PBS/ I have added it to the server, initlaised it, when I add to datastore, I select ZFS, I tries to complete thie initialisation then it comes up with the error below. I do have another HDD but not dure why its throwing this error up, any ideas would be greatly appreciated. I dont think I am trying ot nest the datastore (well not on purposes) Look forward to hearing from you, and thanks in advance.