korg m50 & mpc 1000

ok i had yamaha mo 8 trade it up for m50 sense yamaha was miss up..

but im haveing one same porblem my keyboard switch sounds
ex i can have track 1 bass press stop or anythang on the mpc and every once while will change the sound on my korg to piano or anythang.Why??

I just got the korg m50 yesterday. so cant be miss up

my mpc settings are
follow by the book. on midi track on mpc my program is set to off
ex.
track 5
midi: program - off midi ch 1b

so what do i need do??