Need Help to Control Effect Slots by Midi

[kukiko]

Hello everybody,
I tried to control the effects of my Stage 2 in slot A and B by USB-Midi with a computer. My settings are:
Local off
Global USB 2
Slot A/B USB 3/4
Organ A/B USB 5/6
Piano A/B USB 7/8
Synth A/B USB 9/10
My expectation was, to access the effects on A and B by USB-channels 3/4 respectively. E.g. Amp-Simulation Destination by cc 90 and Amp-Simulation-Type with cc 81.
I have checked the Midi-out of my computer with a midi monitor and the Midi-in of the Stage by the Midi LED.
The computer is sending the correct messages and the NS2 receives the Midi.
The Problem: I can only control slot A, slot B doesn´t respond.
The only difference, I realised was the shorter flickering of the Midi LED on the NS2.
I searched the forum but have found any answer to this problem.
Can anybody help?

[maxpiano]

Nominally it should work... Maybe you also have to switch Slot Focus (cc68) to control Slot B? It would be odd, but worth a try.