[ovirt-users] could not using direct lun

Hello, everyone. I'm new here. I have created an ovirt last week. Version 4.2.6. there are 3 ovirt node hosts in that cluster. the engine is self-hosted. Everything works OK, but I can not create virtual disk using direct lun. When I click storage > disk > new, and select direct lun tab, select storage type :"Fibre Channel", it can find the lun id, but the id is grey, and when I click the lun id, I can not click OK to save the Virtual Disk. I'm using a HPE 3PAR storage device and have granted access to all the 3 hosts in that cluster. Is there any mistake in my step? yours Adam