hey kid collect
lets try to do this again. ask your qestion again. because you mentioned VIA usb? tell us what kind of MPC you are uesing. second, be more specific about the tracks in question.
are you uesing vst instruments?
I ask all this because I have nuendo 2.1.1.25 together with the mophatt and vst instruments all synced up (took me almost 1 month to figuer it out)
to nuendo and all works like a dream. I must say its not easy to set it up because there are settings in nuendo that must be set correctly for this to work and settings in the mpc that must corrispond to the channels in nuendo. Oh ome more thing, what audio interface are you useing to connect the mpc to nuendo?
let me try to answer one of your questions.
if you need the MPC to be a slave to nuendo ,do this
1 take the midi out of your sound card to midi in( 1 ) on the mpc......
connect the left right or(left mono) out put to the input of you sound card.
2 now go to nuendo 2 and look for the tab called transport(open it)
3 go down the list of the transport tab and find "sync setup".
4 once you are in sync setup look for "send midi clock" and choose your sound card in the box below.
5 click ok
6 now,on the mpc press shift (9)
7 where it says sync in (make sure it set to channel 1) and below that set the mode to "midi clock" dont touch the sync out section of this screen.
8 now set up the mpc for what ever bars you want and load up your sounds into the mpc and create a 4 or 8 bar sequence on the mpc.
9 now go back to nuendo and look at the transport bar(thats the floating bar that never goes away with play,stop ,etc

and look to the right of the record button . it will say sync.. make sure it says sync INT.
10 now create a track in nuendo(mono or stereo) arm the track(the red button must be lit and the little orange speaker type button must also be lit.
11 press record on nuendo and you will hear the normal 8 click metronome then the mpc will start to play and nuendo will record what the mpc is playing on the track you created.
this works for me because i do it all the time and it took me a long time to figuer it out. this is just the set up to slave the mpc to nuendo.
you really have to know your system well to inorder to know how to configuer it well and I will help because I know how frustrating it is when all this crappy connections get in the way of the music making.
if im missing something step in anyone