Is there a way to control velocity through an envelope.

[Tekkas]

Hello, i have a composed a simple 8 bar brass section midi loop in live 8 using four chords with each chord lasting 2 bars.When i open the envelope for this clip i would like to draw in a slowly increasing velocity change for each chord but all i could find was volume which isn't cutting it because it is not actually affecting the dynamics or "real" volume if you know what i mean.In other words.....the volume increases but the dynamics of the instrument don't actually change from a low creeping hum to a razor sharp howl of a brass instrument played at full pressure on the midi keyboard.There is probably something simple i have missed here and would greatly appreciate any feedback from anyone who has the time to offer a simple answer.

regards,