Unable to Access Barometer (BMP180) using Python on Raspberry Pi

Question

I have a BMP180 barometer which I'd like to read using Python on a Raspberry Pi.

I've followed the Adafruit tutorial and have been successful in readING data using sudo i2cdetect -y 1 but I get an error when I attempt to run simpletest.py in the Adafruit Python BMP library.

pi@raspberrypi ~/Adafruit_Python_BMP $ sudo python examples/simpletest.py
Traceback (most recent call last):
  File "examples/simpletest.py", line 37, in <module>
    sensor = BMP085.BMP085()
  File "/usr/local/lib/python2.7/dist-packages/Adafruit_BMP-1.5.0-py2.7.egg/Adafruit_BMP/BMP085.py", line 68, in __init__
    self._load_calibration()
  File "/usr/local/lib/python2.7/dist-packages/Adafruit_BMP-1.5.0-py2.7.egg/Adafruit_BMP/BMP085.py", line 71, in _load_calibration
    self.cal_AC1 = self._device.readS16BE(BMP085_CAL_AC1)   # INT16
  File "/usr/local/lib/python2.7/dist-packages/Adafruit_GPIO-0.9.3-py2.7.egg/Adafruit_GPIO/I2C.py", line 195, in readS16BE
    return self.readS16(register, little_endian=False)
  File "/usr/local/lib/python2.7/dist-packages/Adafruit_GPIO-0.9.3-py2.7.egg/Adafruit_GPIO/I2C.py", line 172, in readS16
    result = self.readU16(register, little_endian)
  File "/usr/local/lib/python2.7/dist-packages/Adafruit_GPIO-0.9.3-py2.7.egg/Adafruit_GPIO/I2C.py", line 159, in readU16
    result = self._bus.read_word_data(self._address,register) & 0xFFFF
IOError: [Errno 5] Input/output error

I've also tried using Adafruit's Adafruit-Raspberry-Pi-Python-Code library but I get a similar I/O related error.

pi@raspberrypi ~/Adafruit-Raspberry-Pi-Python-Code/Adafruit_BMP085 $ sudo python Adafruit_BMP085_example.py
Error accessing 0x77: Check your I2C address
Error accessing 0x77: Check your I2C address

Does anyone have any idea why this is the case? I am using a Raspberry Pi 2 Model B.