can you provide a little more info, OS, what steps you are taking to get to the point where you enter the command? Does this work on other systems you have tried and the R300 is the only one that fails?

Trying this on a Debian 5.0.4

I have installed ipmitool using apt-get

Then did

 modprobe ipmi_devintf                          
 modprobe ipmi_msghandler                          
 modprobe ipmi_poweroff                         
 modprobe ipmi_si  
 modprobe ipmi_watchdog 

I can run other ipmi commands without a problem, ie:

ipmitool lan print

I've run 'ipmitool -I open chassis status' on a R710, and the results match the actuall BIOS settings. 

However, running same command on a R300 gives 'Power Restore Policy' as 'always-off', 
and I have checked this and it is actually on.

oh, and are you doing this inband or out of band?

let me check a few things, I'm guessing your R300 doesnt have an Idrac and your R710 does. Could be a BMC problem in that it may not be processing the request due to a fw bug.

As I don't actually know what iDRAC is, then this might be the case.

I'm making the requests on the server, via ssh root access