mpk and mpc 4k?

ok im using a mpc 4k,logic 9 and a mpk 61 aas a midi controller,now i have the midi controller working fine with logic but i also want to use it with my 4k to play sounds from mpc,but for some reason the 4k doesnt seem to be getting midi signal from the mpk? i have a midi cable going out of the mpk to the input of the 4k shouldnt i be able to play the sounds?

If you are going to use the MIDI ports on the MPK you have to use a power adapter.
Also on the MPK you can't use the USB port and the MIDI port at the same time. It's one or the other you go to use.

ok well that explains it!!!

thank you