cannot output specific layer

[sp5084]

When I am trying to plot a single layer, using the exact same line of code as provided by the author, it is somehow showing only a red picture. I typed the coding in Visual Studio Code as below:

import os
os.system('py gcode_reader.py -t 1 octo.gcode -l 1')

However, the output is as below:

It is the same no matter which layer I specified. The output is the same as above even if I changed to the 40th layer.

What may be wrong? I would appreciate any help.

[sp5084]

I might add that when plotting the example octo.gcode in 3D, it is showing the same result as the example.

However when using animation, it is showing the below error:
gcode_reader.py: error: argument -a/--animation: expected one argument

Only the plot 3D is working for me. Should there be anything that I need to tune in the code before using it? I am grateful for any help!