Thanks.
I have data.
I can see data from TW dashboard.
The JSON file contains this response.
{“data_type”:“stats”,“time_series_length”:61,“data”:[],“request”:{“params”:{“start_time”:“2016-03-31T15:00:00Z”,“segmentation_type”:null,“entity_ids”:["***"],“end_time”:“2016-05-31T15:00:00Z”,“country”:null,“placement”:“ALL_ON_TWITTER”,“granularity”:“DAY”,“entity”:“CAMPAIGN”,“platform”:null,“metric_groups”:[“MOBILE_CONVERSION”,“BILLING”]}}}