flowdroid_fields empty

I get an issue when I try to run this framework for feature extraction. Why flowdroid_fields is empty?
	
	flowdroid_fields = apk_dict_example["Static_analysis"]["FlowDroid"].keys()

    |						└ OrderedDict([('Pre_static_analysis', OrderedDict([('Filename', 'a.envisionmobile.caa.apk'), ('md5', '31bf2eb9555403d764d8741c9cb...

    └ []

		KeyError: 'FlowDroid'

