trying to use specific country for node selection in tor

[Sambuddho Chakravarty]

Hello All
 I am trying to use specific country selection in the torrc as per the 
FAQs in the Tor website. The following is a snippet from my torrc

...

EntryNodes {us}
ExitNodes {us}

StrictEntryNode 1
StrictExitNode 1


However when I run tor - 0.2.1.15 with this configuration , I get the 
following error message :-


Jun 13 01:49:15.860 [warn] Failed to parse/validate config: IPs or 
countries are not yet supported in EntryNodes.


Am I doing something wrong ? Is there some other way to specify which 
countries to use for entry,middleman and exit node selection  ?


Thanks
Sambuddho