when I ran command below to calibrate realsense D435i rgb cemera, the bug always appears

command: kalibr_calibrate_cameras --target ~/project/calibration/rgb/april_6x6_A4.yaml --bag ~/disk/datasets/realsense-dataset/calibration/rgb/rgb.bag --models pinhole-radtan --topics /camera/color/image_raw --bag-from-to 20 80 --show-extraction

Cameras are not connected through mutual observations, please check the dataset. Maybe adjust the approx. sync. tolerance.
Traceback (most recent call last):
File "/home/n609/software/kalibr_workspace/devel/bin/kalibr_calibrate_cameras", line 15, in
exec(compile(fh.read(), python_script, 'exec'), context)
File "/home/n609/software/kalibr_workspace/src/kalibr/aslam_offline_calibration/kalibr/python/kalibr_calibrate_cameras", line 447, in
main()
File "/home/n609/software/kalibr_workspace/src/kalibr/aslam_offline_calibration/kalibr/python/kalibr_calibrate_cameras", line 204, in main
graph.plotGraph()
File "/home/n609/software/kalibr_workspace/src/kalibr/aslam_offline_calibration/kalibr/python/kalibr_camera_calibration/MulticamGraph.py", line 311, in plotGraph
edge_label=self.G.es["weight"],
KeyError: 'Attribute does not exist'

I try to add --approx-sync like this:
kalibr_calibrate_cameras --target ~/project/calibration/rgb/april_6x6_A4.yaml --bag ~/disk/datasets/realsense-dataset/calibration/rgb/rgb.bag --models pinhole-radtan --topics /camera/color/image_raw --bag-from-to 20 80 --show-extraction --approx-sync 0.01

but it doesn't work.and I try to change the Hz of rgb cemera.but it doesn't work too. now I don't know how I can solve it. Anyone body know how to fix the problem? if you know , please tell me ,thanks very much!