xpcshell can't get nsJSRuntimeService

Hi,

I'm trying to test a component using xpcshell, but whenever I try to 
start it up, I get an error telling me it can't get nsJSRuntimeService:

angstrom:~/Development/mozilla/dist/bin tony$ ./run-mozilla.sh 
./xpcshell
failed to get nsJSRuntimeService!

I've only just started playing around with Mozilla and I was following 
the instructions in Creating Applications with Mozilla, but it seems 
xpcshell can't even initialize itself. I updated my source tree from 
CVS today before building.

Can anyone give me some insight into how I can get this working, or if 
this is a known problem?

Thanks,
Tony