how to integrate aws drivers to openstack

I have tried intgrating aws drivers to openstack train, i was trying glance at first but came to an error showing aws driver not found. I then installed openstack liberty as mentioned in glance readme...but still i am getting the same error...

I have copied the driver codes to <root>/glance_stores/_drivers and edited the /etc/glance/glance-api.conf, changed the stores and default_store to aws like ,

[glance_store]
   default_store = aws
   stores = aws
   show_multiple_locations = true

  [AWS]
   secret_key = <your aws secret access key>
   access_key = <your aws access key>
   region_name = <was region to use>

and then restarted the glance-api service, then the error pops up...

WARNING glance_store.backend [-] Failed to load driver [<module 'stevedore.driver' from '/usr/lib/python2.7/dist-packages/stevedore/driver.pyc'>, RuntimeError("No 'glance_store.drivers' driver found, looking for 'aws'",)].The driver will be disabled.

Please help to debug the issue...
I have to ultimately try it on openstack train.

Thanks in advance