Hi Paul,
Thanks for information.
I could not find certain information to resolve the problem but I just found a web page showing that RHEL 6.6 is not supported for every version of MOFED - MLNX_OFED: Firmware - Driver Compatibility Matrix - Mellanox Technologies
I don't know exactly why but you might need to evaluate the installation with another version of RHEL referring to the instruction.
(Btw, in our case in the past, one of the recent version of MOFED was successfully installed on our server that was running with CentOS 6.7.)
Once you've installed MOFED on your host, you will be able to check if it is properly running using this command:
# hca_self_test.ofed
I hope the issue is resolved sooner.
Thanks,
Masa