Not getting output from SPI

Hi,
I just purchased my new Beaglebone Black and trying to implement SPI on that. I have written this simple code for writing a byte of data using Adafruit_Python_GPIO library.

import Adafruit_GPIO as GPIO
import Adafruit_GPIO.SPI as SPI
from MockGPIO import MockGPIO

gpio = MockGPIO()
device = SPI.BitBang(gpio,“P8_7”,“P8_8”,“P8_9”,“P8_10”)
#device.set_mode(0)
#device.set_bit_order(0)
device.write([0xAA])

It is not showing any error but i’m not getting any waveforms at any GPIO.
Note: Used normal GPIO because BitBang is for software SPI.