usb_relay_device_enumerate return Null pointer access

[super-starha]

I download USB_RELAY_DEVICE.dll and use lib.usb_relay_device_enumerate(), but it return NUll pointer access,
please help me to take a look.Thanks very mush
Traceback (most recent call last):
File "F:\SelfProject\TrainPython\venv\lib\site-packages\automotive\utils\usb_relay.py", line 105, in usb_relay_device_enumerate
p = resp.contents
ValueError: NULL pointer access

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
line 324, in open_relay_device
dev = self.__lib.usb_relay_device_enumerate()
in usb_relay_device_enumerate
raise RuntimeError(error[1])
RuntimeError: NULL pointer access