Cubase Midi device/Midi panel/Sysex Generic Message/Parameter assignation

Hi,

I have a sysex generic message with two value:
Attack (0-7) three first bit
Attack velo (0-7) bit 456

I have created two parameter:
Attack
Attack Velo

Anyway i got this for the Attack parameter:
Attack x
Attack velo 0

And this for Attack velo parameter:
attack 0
Attack velo x

What do i need to do have both at the same time in the transmission message:
attack x (where x is from the attack parameter)
Attack velo x (where x is from the attack velo parameter)

Or does cubase does it automatically?

Thanks in advance,
Have a good day,
Rgds,