Make sure you are using Liquid Control V1.1.2 - this is Tiger compatible and is available to download at www.focusrite.com Firmware version 1.1.0 needs to be installed on the Liquid Channel.  If the unit has an earlier version of the Firmware then turn the unit on and connect it via USB to the computer.  Now when Liquid Control is opened the application will prompt you to update the Firmware and give instructions.  The current installed firmware version number is displayed when the Liquid Channel is turned on.