Cannot run rqt_bag_diff

[JoanaMota]

When running the package as follows:

$ rosrun rqt_bag_diff rqt_bag_diff

I get the following error when selecting the bag file:

Gtk-Message: 16:57:59.176: GtkDialog mapped without a transient parent. This is discouraged.
This is the LAST event.
Traceback (most recent call last):
  File "/home/mja2brg/test_ws/src/rqt_bag_diff/src/rqt_bag_diff/bag_widget.py", line 315, in _handle_load_clicked
    self.load_bag(filename[0])
  File "/home/mja2brg/test_ws/src/rqt_bag_diff/src/rqt_bag_diff/bag_widget.py", line 385, in load_bag
    self._event_selector_1_selected(eventnames[0])
  File "/home/mja2brg/test_ws/src/rqt_bag_diff/src/rqt_bag_diff/bag_widget.py", line 400, in _event_selector_1_selected
    self._timeline_1.translate_timeline_event_right(name)
  File "/home/mja2brg/test_ws/src/rqt_bag_diff/src/rqt_bag_diff/bag_timeline.py", line 585, in translate_timeline_event_right
    event_stamp = self.event_filters[name].next_event_stamp().to_sec()
  File "/home/mja2brg/test_ws/src/rqt_bag_diff/src/rqt_bag_diff/bag_timeline.py", line 84, in next_event_stamp
    return self._timestamps[returnMe]
IndexError: list index out of range
Aborted (core dumped)

I am selecting a bag file and the copy bag file is exactly the same ( just did Ctr+C and Ctr+V to generate a copy file just to test)

Can anyone help?