I'm trying to execute smartctl and I'm getting this:

root@localhost:~# /usr/sbin/smartctl -a /dev/sda
smartctl version 5.33 [x86_64-redhat-linux-gnu] Copyright (C) 2002-4 Bruce Allen
Home page is http://smartmontools.sourceforge.net/

Device: MegaRAID LD0 RAID5 40012R Version: 1L37
scsiModePageOffset: response length too short, resp_len=1 offset=4 bd_len=0
>> Terminate command early due to bad response to IEC mode page
A mandatory SMART command failed: exiting. To continue, add one or more '-T permissive' options.

I've tried '-T permissive' option without success, any help ?
Thanks in advance.