this is a known bug & JJ says it is uncorrectable.
but c'mon now... how can this be 'uncorrectable'? total nonsense.
more likely, JJ just doesn't know how to correct it.
anyway, from JJs FAQ page:
Q:
FX SEND level not working.
1. goto [GLOBAL PROGRAM EDIT MODE]
2. choose [OUT]
3. goto [EFFECT]
4. move cursor to [FX1]
5. choose [REVERB]
6. move cursor to [FX2]
7. choose [DELAY]
8. move cursor to [OFF] - between FX1 & FX2
9 switch on [SEND]
9. the send level doe's nothing - it doe's not attenuate the reverb level being sent to the delay.
this is the same for other combinations of effects.
A:
This is a bug uncorrectable although it is a bug.