vSphere Read Cache - no disk is found

Hi all,

ESXi 5.5 ent+

HP BL460c Gen8 with P220i array controller

Intel SSD DC S3700 200 GB (Intel disk is supported, also tried with Samsung 960 GB SSD)

I have a problem with adding a SSD disk in web client. I click Manage - Settings - Virtual Flash Resource Management - Add capacity, but the list i empty.

Both disks are visible if looking on storage adapters, it is fully possible to add them as a datastore, which I tried on the Samsung without any success.

The disks have been used for PernixData evaluation and worked well there.

Any suggestions?

Thanks!