rally min_ram error

2016-01-26 01:19:22.839 19584 ERROR rally.task.scenario [-] 'min_ram'
2016-01-26 01:19:22.839 19584 ERROR rally.task.scenario Traceback (most recent call last):
2016-01-26 01:19:22.839 19584 ERROR rally.task.scenario   File "/usr/lib/python2.6/site-packages/rally/task/scenario.py", line 116, in _validate_helper
2016-01-26 01:19:22.839 19584 ERROR rally.task.scenario     deployment=deployment)
2016-01-26 01:19:22.839 19584 ERROR rally.task.scenario   File "/usr/lib/python2.6/site-packages/rally/task/validation.py", line 64, in wrap_validator
2016-01-26 01:19:22.839 19584 ERROR rally.task.scenario     return (fn(config, clients, deployment, *args, **kwargs) or
2016-01-26 01:19:22.839 19584 ERROR rally.task.scenario   File "/usr/lib/python2.6/site-packages/rally/task/validation.py", line 352, in image_valid_on_flavor
2016-01-26 01:19:22.839 19584 ERROR rally.task.scenario     if flavor.ram < (image["min_ram"] or 0):
2016-01-26 01:19:22.839 19584 ERROR rally.task.scenario KeyError: 'min_ram'
2016-01-26 01:19:22.839 19584 ERROR rally.task.scenario

Task config is invalid: `Input task is invalid!

Subtask NovaServers.boot_and_delete_server[0] has wrong configuration\Subtask configuration:
{'runner': {'type': 'constant', 'concurrency': 1, 'times': 1}, 'args': {'nics': [{'net-id': '42a02ea4-971c-459a-ac22-4cce38b98cee'}], 'flavor': {'name': 'm2.small'}, 'image': {'name': 'e2-image'}}, 'sla': {'failure_rate': {'max': 10}}}

Reason:
 Invalid scenario argument: ''min_ram''