VirtualBox: why there is no Passthrough checkbox on Storage screen?

[Yuri]

All conditions from section 23.3.3 are satisfied (atapicam is in kernel 
and device permissions are right).
But storage screen only allows me to select some iso file to export into 
guest. Passthrough checkbox never shows up on the Storage window.
For example, under IDE I see "IDE Primary Master", etc choices, it says 
CD/DVD Drive but never offers passthrough (checkbox always stays invisible).

How to understand why isn't passthrough available?

DVD drive is recognized by system as:
cd0 at ata2 bus 0 scbus9 target 0 lun 0
cd0: <PIONEER DVD-RW  DVR-112D 1.21> Removable CD-ROM SCSI-0 device


Yuri