LUN Could not be created: ...it would have left the array operating over its Safe Operating Capacity

I have an NS-120 (cx4-120) and I am trying to create a 50 GB LUN.  There is 17 TB unused capacity and we are no where near a max LUN count.  I am trying to create a LUN in our one and only POOL0.

Any ideas why I would get this message?  I have read through some threads that mention using the EPC Enabler.  Not sure what that is.

I am creating this LUN to be used a secondary mirror of a lun on our new VNX 5400.  Yesterday I was getting the same error when trying to create the LUN using the mirror wizard so I had to unisphere directly to the ns-120 and create the LUN first, then designate it as the secondary mirror.  Today I get the error creating the new LUN directly from unisphere connection to either SPA or B.

Driving me nuts!!

Thanks,

C