Anyone know what this error means when I try to load certain Cisco MIBs?

Error detected while loading MIB file \usr\ov\...MIB...
This MIB cannot be loaded until the following problem is corrected.

Line xx    Error defining object '..MIB..' : Parent 'ciscoMgmt' not defined.

The Line xx number will change values according to the Cisco MIB I try to
load.

Thanks,

Larry