Loading midi songs

Hello,
I just purchased the MPC500 last week with the assumption that I could save/ upload existing Midi songs on my PC to the MPC500. I tried the load and save option based on the MPC guide, however, it seems that only certain tracks are loaded to the MPC, and not all the tracks, such as the piano and bass instruments.
Can someone please provide with any advise?
I would really appreciate it.
Regards,

you load wav files into the mpc,. you know, mpc's are really behind the times, i mean, dont get me wrong, i love my 500, but 4 real, its like a dinosaur compared to other stuff,. think of the mpc as the 8-track in the age of the cd..

yo, chejito, here is a post with ur question,, alot of these same questions have been asked already long ago,, good luck..
http://www.mpc-forums.com/viewtopic.php?f=26&t=79041