First check device id and bus-id you are using during the initialization of spi (i.e. onionSpi.OnionSpi(1, 32766)
SPI is done through an adapter usually found at /dev/spidevX.Y where X is the device number and Y is the bus number, so in my case 1 is bus id and 32766 is device id

you can find your details under : /dev/ folder of your omega where file spidev would tell details for you as in above line or at below official ref.

Use Ref: https://docs.onion.io/omega2-docs/spi-python-module.html

hope you have resolved, if still any issue please revert here...

Thanks