I am getting the following error trying to retrive DOW ticker. 

Runtime Error: Trying to retrieve an element from a collection using a key that does not exist in that collection throws a KeyError exception. To prevent the exception, ensure that the DOW key exist in the collection and/or that collection is not empty.
at OnData in main.py:line 111
KeyError : 'DOW'

From 2017/1/1 up to today. Hourly candle.