johnnyrock - As a thought, try renaming the "/usr/share/ibdiagnet2.1.1" directory out of the way first.
eg:
# mv /usr/share/ibdiagnet2.1.1 /usr/share/ibdiagnet2.1.1_old
# ibdiagnet --get_cable_info
... output here ...
I'm not sure if that will make the "--get_cable_info" parameter succeed, but I remember having to do that last week to stop the error message happening for ibdiagnet in general (with Mellanox OFED on RHEL/CentOS 6.x).
(note - edited for typo fixes)