unable to run the sample code

Nov 2, 2011 at 7:40 PM

Hi 

I am getting the following error when i run a-Expense (claims aware) site. 

Error: 'ID1039: The certificate's private key could not be accessed. Ensure the access control list (ACL) on the certificate's private key grants access to the application pool user.

What did go wrong ? I run the dependency and everything is successfully run. 

thanks