Changing the volume of midi keyboard notes on the MPC2000xl

I have recently bought a Novation KS4 keyboard which i have started using in conjunction with the MPC2000xl. On a recent track i have used the KS4 to make a bassline. However, in order for the bassline to fit with the sample i have to use some lower notes as well as higher ones (obviously). The lower notes, when played under the sample, sound much quieter than the higher bass notes because they are at a lower pitch. When i try and increase the velocity (volume) of the lower notes on the MPC so they are not drowned out by the sample, nothing seems to happen. Basically what i am asking is how can i use the MPC to increase the volume of individual notes on the keyboard?

Hopefully this makes sense to someone.

Thanks in advance.

Step edit is a good start point or highlight velo% and hit open window. C'mon man, u gotta get with it. This is basic stuff

I have already tried both your suggestions prior to posting my original message, as i mentioned in my original post. In theory its basic stuff, but changing the velocity of the note in step edit or highlighting velo% and changing it seems to make no difference to the volume of the keyboard note coming out of the speakers. I know this works when using samples but it doesn't seem to work using MIDI. Why?

Works for me...U may find pg 127 of the manual helpful if ur still having a hard time