Thank you so much for your reply.
I have followed all you steps. Now I can see the equipment appears in my test server, however other than ON/OFF status, the rest are unknown. Previously I have changed Encryption Key on IDRAC7 before, I suppose that now I changed it back to "000000", so that it matches with what I keyed into OME, right?
The test IPMI alert that sent from iDRAC is also not received on the test server.