DMP ctlr path DISABLED

If vxdmpadm shows a path/ctlr as DISABLED, how can you tell if it has been disabled by "vxdmpadm disable" or if there is a hardware issue.

So for example I see:

Q192EYU@gbahex147 # vxdmpadm listctlr enclosure=st2540-1
CTLR_NAME       ENCLR_TYPE      STATE        ENCLR_NAME      PATH_COUNT
=========================================================================
c2              ST2540-         DISABLED     st2540-1             1
c5              ST2540-         ENABLED      st2540-1             1

Q192EYU@gbahex147 # vxdmpadm getsubpaths enclosure=st2540-1
NAME         STATE[A]   PATH-TYPE[M] DMPNODENAME  ENCLR-NAME   CTLR    ATTRS
================================================================================
c2t4d0       DISABLED   SECONDARY    c2t4d0       st2540-1     c2        -
c5t1d0       ENABLED(A) PRIMARY      c2t4d0       st2540-1     c5        -

I suspect it is a hardware issue as I can't enable:

Q192EYU@gbahex147 # vxdmpadm enable ctlr=c2
VxVM vxdmpadm ERROR V-5-1-2395 Invalid arguments

Q192EYU@gbahex147 # vxdmpadm enable path=c2t4d0
Q192EYU@gbahex147 # echo $?
0
Q192EYU@gbahex147 # vxdmpadm getsubpaths enclosure=st2540-1
NAME         STATE[A]   PATH-TYPE[M] DMPNODENAME  ENCLR-NAME   CTLR    ATTRS
================================================================================
c2t4d0       DISABLED   SECONDARY    c2t4d0       st2540-1     c2        -
c5t1d0       ENABLED(A) PRIMARY      c2t4d0       st2540-1     c5        -

I don't understand why I get "Invalid arguments" and I would have thought I should get an error and non-zero exit code if I tried to enable path.  Are there any commands/logs I can look at to confirm this is a hardware issue?

Mike