Sort for chart not working

Hi, I'm doing a search on the _internal index for license usage by host. I'd like the histogram to have the biggest values of X by Y on the left and I've been searching here for half an hour and it seems that what I am trying to do should be working, but it isn't. Can anyone point out the issue? Here is my search: `index=_internal source=*license_usage.log type=Usage | eval MB = round(b/1024/1024,1) | chart sum(MB) as MegaBytes by h | rename h as device | sort –MegaBytes`