12cR3-Discover newly added hardware on Existing exadata machine as target

Hi Experts,

My customer is using 12cR3 and monitoring the exadata machine quarter rack.

so the agent is running on the each db node.

if the exadata machine extends to half rack, 2db nodes&4cell nodes are added as you know.

He wants to discover the newly added db&cell nodes on existing exadata machine.

I try to do following on em12cR3 console.

[Add Target Manually -> Using Non-host guide -> select Exadata database machine -> select Discover newly added hardware components on existing database machine as target]

But only the Compute Nodes are not shown. The Cell Nodes are visible.