After following the Quick Start Guide I am getting an ERROR:

The hibernate.connection.driver_class must be specified in the 
NHibernate configuration section

I have clearly declare the hibernate.connection.driver_class Key in 
app.config file:

 <add key="hibernate.connection.driver_class" 
value="NHibernate.Driver.SqlClientDriver" />

I am stucked up with this. Kindly help to solve this prob. 

Thanks,