Twython does not get back next_results

I am trying to get more than 100 tweets by twython but it does not get back next results in search_metadata of results. It get:

{'completed_in': 0.098, 'max_id': 935489442785251328, 'max_id_str': '935489442785251328', 'query': '%22iran%22+-filter%3Aretweets', 'refresh_url': '?since_id=935489442785251328&q=%22iran%22%20-filter%3Aretweets&include_entities=1', 'count': 100, 'since_id': 0, 'since_id_str': '0'}

any suggestion, what is the problem?