Velocity control in ableton

in the prog house tut at the end of the bass vid the velocity controls are adjusted to get a different sounding rhythm, wel when i move mine up or down it doesnt sound any different if its at the top or bottom!!!

why is this?

something wrong with my ableton??

ive actually jus realized that you need to turn th velocity up in th simpler device!!

but still dont know how to do it on the sylenth bass notes!!