Error with OAuth instance 2legged

[GoogleCodeExporter]

hi all,
i have some error report when trying to using the source codes from this url :
https://code.google.com/p/oauth-php/wiki/ConsumerHowTo#Two-legged_OAuth

error report :
Notice: Undefined property: OAuthStore2Leg:

i think its refers to OAuth lib. can you guys tell me what should i do to fix 
this problem?

PS : im using windows as my os.

Original issue reported on code.google.com by [email protected] on 7 Aug 2013 at 9:09