The other two are only used if you use the SPI interface, which you don't seem to use. Wiring sounds OK. For SPI wiring and how to set the sensor to SPI mode, check the documentation of your specific breakout board.
Do you have pull-up resistors on SDA and SCL? (this may or may not be on your breakout module - if not, you have to add external ones - 10k is usually fine). It may be that your Arduino's internal pull-ups are used, which are out of spec for I2C, but could be enough for the scanner to find the device, but not good enough to do more communication with it.
Is that a 5V or 3.3V Arduino? If 5V you need level shifting (again this may or may not be on board of the module).