I found out that if my Butterfly labs' miner refuses to be recognized by cgminer with the message BitForceSC detect (??:??) failed to initialise (incorrect device?),

For my macbook pro, the solution is to install the FTDI USB Serial Driver again. I have to do it every time I reconnect the device, but it works.

The drivers can be found here: http://www.ftdichip.com/Drivers/VCP.htm