e-Paper 4.2 inch with Python not working on Raspberry Pi 3B+

[jason19970210]

As mentioned in subject.

I had installed dependencies, then wired up with the documentation, starting the example program. The code runs well, but nothing displayed on the screen.

The SPI interface is also enabled.

Board:           Raspberry Pi 3B+
OS:              Raspbian GNU/Linux 11 (bullseye)
Kernel:          5.15.84-v7+  armv7l
Python Version:  3.9.2
Pip Version:     20.3.4

Module: 4.2 inch e-Paper (Rev: 2.1) (400x300 pixel)

$ sudo apt install python3 python3-pip python3-pil
$ pip3 install Rasp-GPIO

$ python3 epd_4in2_test.py

Thanks for the help.

[shhds]

python3 epd_4in2_test.py be refitted into sudo python3 epd_4in2_test.py