It looks like your sudo is not working or installed correctly pn your system as it has no affect at all. Which Linux distribution do you use?
Also what I've noticed is it seems to be this line that totally blanks out the diskspace :
$go_info["server"]["sudo_du_enabled"] = 0; // enable sudo for gathering website file usage
When I change that to a 1 instead of the 0, then my stats don't show anything at all except the mysql data.
Thats just the symptom and not the cause.