I know my mx49 has no aftertouch. But i Have a gem s2 masterkeyboard with aftertouch.i read somewhere that the aftertouch potentional can be used triggered in the mx by midi
So far no luck, aftertouch in the gem works. If i use midi everything works okee but no aftertouch effect alas.
Any suggestions ?

It’s possible (likely?) that the factory voices of the MX weren’t programmed to respond to aftertouch.

I agree with Meatball: the voices probably aren’t programmed for aftertouch since it’s not an “included” function on the MX keybed. The MX tone generator should respond to aftertouch commands though. On the old “classic Motif” you could assign aftertouch to things like low freq oscillators (Leslie effect, vibrato, etc) but I haven’t tried anything like that with the MX. I suppose it could be done with an external program but don’t know which one to suggest.