Key command for Mixer Fader

hi there could anybody tell me if there is a Key command for the Mixer Fader in cubase 6.5 ,in cubase 4 and 5 it is the arrow up/down key ,but this command does not work in 6.5. i can not find the action name in key commands i have looked under - fader,volume ,bus volume fader ,mixer , i can`t find anything what describes the action of adjusting the mixer fader to be able to assign a key to it . thanks