vmfs_spanning RC: 5147 error

I'm getting the following error when trying to run the vmfs spanning test.

[Aug 20 2015 18:22:00 : VMSTAF    ] [0] ERROR: Error submitting request, RC: 5147
[Aug 20 2015 18:22:00 : VMSTAF    ] [0] ERROR: Command 'staf local VTAF_HOST addextent host cos-qa-qvm04 anchor cos-qa-vcenter5:administrator datastorename AddExtent_Volume lunname naa.6001f931031680000111000200000000' FAILED.
[Aug 20 2015 18:22:00 : VMSTAF    ] [0] ERROR: Additional information: javax.xml.ws.soap.SOAPFaultExceptionCannot change the host configuration.
[Aug 20 2015 18:22:00 : VMSTAF    ] [0] ERROR: Required STAF operation failed. Subsequent test steps may not function.
[Aug 20 2015 18:22:00 : HOST      ] [0] ERROR: Failed to add extent naa.6001f931031680000111000200000000 to volume AddExtent_Volume.
[Aug 20 2015 18:22:00 : ADDEXTENTS] [0] ERROR: Add extent naa.6001f931031680000111000200000000 to datastore AddExtent_Volume failed.

Is there any particular reason why this is constantly coming up?