[c-nsp] [sanity check] cipMacSwitchedBytes works, but cipMacHCSwitchedBytes doesn't?

[Aaron Glenn]

I cannot, for the life of me, poll the 64bit counters under the
cipMacHCTable on this 6504. Clearly its supported - please hit me with
a cluebat at your earliest convenience. (interfaces
desc and mac/ip addresses changed to protect the guilty)

sh ver:
Cisco Internetwork Operating System Software
IOS (tm) s72033_rp Software (s72033_rp-IPSERVICES_WAN-M), Version
12.2(18)SXF7, RELEASE SOFTWARE (fc1)

sh ru:
interface GigabitEthernet1/2
 description mac_accounting_enabled
 ip address 222.233.244.255 255.255.255.0
 ip accounting mac-address input
 ip accounting mac-address output
!

sh int mac:
GigabitEthernet1/2 mac_accounting_enabled
  Input  (465 free)
    0017.cb5e.8f12(22 ):  3475 packets, 290906 bytes, last: 26992ms ago
    0005.6da1.5680(24 ):  2697 packets, 198785 bytes, last: 2052ms ago
    0090.6944.b217(24 ):  3789 packets, 347726 bytes, last: 20212ms ago
...snip...
    0007.b393.a019(110):  21047 packets, 1759695 bytes, last: 1212ms ago
    0014.f2b4.db0f(137):  3 packets, 180 bytes, last: 6254276ms ago
                  Total:  134480 packets, 11798511 bytes
  Output  (445 free)
    000a.8b0d.b9b2(7  ):  2281 packets, 307819 bytes, last: 36196ms ago
    0017.cb3e.8f13(22 ):  3426 packets, 464815 bytes, last: 2020ms ago
 ...snip...
    00d0.2b7d.2e54(252):  1956 packets, 267993 bytes, last: 12508ms ago
    0015.c767.4820(253):  1729 packets, 234653 bytes, last: 18120ms ago
                  Total:  228437 packets, 31321727 bytes

sh ru | inc snmp:
snmp-server community public RO 25
snmp-server location closet
snmp-server contact charlie at root.com

I can walk .1.3.6.1.4.1.9.9.84.1.2.1 without issue, but attempting to
walk .1.3.6.1.4.1.9.9.84.1.2.3 ends in a dreaded
"enterprises.9.9.84.1.2.3 = No Such Object available on this agent"

what in the world am I missing?

thanks,
aaron.glenn