You’ll need to dump BRLTTY, remove the package from your distribution.
http://www.ladyada.net/learn/arduino/lesson0-lin.html
If you see something like this
[ 1900.712000] ftdi_sio 2-10:1.0: FTDI USB Serial Device converter detected
[ 1900.712000] drivers/usb/serial/ftdi_sio.c: Detected FT232BM
[ 1900.712000] usb 2-10: FTDI USB Serial Device converter now attached to ttyUSB0
[ 1901.868000] usb 2-10: usbfs: interface 0 claimed by ftdi_sio while ‘brltty’ sets config #1
[ 1901.872000] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now disconnected from ttyUSB0
[ 1901.872000] ftdi_sio 2-10:1.0: device disconnected
That means you have not uninstalled brltty and you should try again.
http://wiki.laptop.org/go/Serial_adapters
Conflict with Braille TTY (brltty) software
Ubuntu distros come with the brltty package installed. This package conflicts with using the device as a plain serial port. Upon insertion the brltty driver takes over the device and disconnects the /dev/ttyUSBn device. The solution to this is to remove or disable the brltty package. On Ubuntu you can do this with
sudo apt-get remove brltty