Rosbag python timestamp read

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Hello guys , I have the following function:

    import rospy, time
    import rosbag

    def test_function(self, topics_dict, start, stop):
    bag = rosbag.Bag('test.bag')
    topic_msg_list = []
    startTime = rospy.Time.from_sec(start)
    print starTime
    stopTime = rospy.Time.from_sec(stop)
    print stoPime
    for topic, msg, rb_tmstmp in bag.read_messages(topics_dict, start_time=startTime, end_time=stopTime):
        print "im in"
        for msg_to_check in topics_dict.get(str(topic)):
            print msg

I use it like the following:

rb.test_function({'/topic': ['message']}, 1502709999.42, 1503000000.61)

But i never get to see the printed output even the 'im in'. What is the problem with the timestamps? Thanks