Cannot create datastore vCenter 5.5

[DirtyBessFlint]

I have a Drobo B1200i with 22TB of empty space on it connected by iScsi.  I created a 1TB volume on it, selecting the multi-host option.  I connected to it using the iSCSI Software Adapter.  It appears to connect and mount properly, both the Drobo Dashboard and the vSphere client show it is connected.  When I try to create a new datastore, it finds my LUN and I can select it, I chose the VMFS-5 file system, the current disk layout says there is only one primary partition.  After I click finish it spins for a while and then comes back with the following error.

Call "HostDatastoreSystem.CreateVmfsDatastore" for object "datastoreSystem-9" on vCenter Server "vcenter" failed.

What am I doing wrong?  Any advice would be very much appreciated.

[npadmani]

see if entries in following post helps

Unable to create VMFS partition - www.ivobeerens.nl‌

Following official KB might give you some more inputs on the same matter

VMware KB: Troubleshooting the Add Storage Wizard error: Unable to read partition information from t...

[continuum]

The GUI does not allow you to create 2 VMFS partition on a single LUN.
You could work around that by creating the second partition via vmkfstools.
But though that is possible I would not recommend it
If the 22tb LUN can be resized - create a second LUN and use the new LUN for the second VMFS-volume.
If you dont have any VMs in the first LUN - delete the LUN and create new volumes and new iscsi-targets.

[DirtyBessFlint]

Thank you very much for your suggestions.  I will be in the office tomorrow and give them a try.  I'll let you know what happens.