While the lack of a midi connection doesn't allow you to sync your tracks up while tracking(unless you buy an outboard midi interface) you can record your tracks into PT through the MBox. You're probably just missing a step somewhere. So here's a lil step by step that should work:
Take some 1/4 inch audio cables and plug them into the outputs on the MPC, from there run them to the inputs on the MBox(or use a spdif cable from the spdif output on the MPC to the spdif input on the MBox)> on the front panel of the MBox there are Source buttons, push these until the green led is lit over the word "line" for inputs 1 and 2> push play on the MPC and turn up the trim knobs until the red clip led lights up and then lower the trim until it doesn't light anymore>if you're monitoring through the MBox turn the input/playback knob all the way to the left> in PT now go to the Setups tab and click on I/O setup> click on the input tab and hit the default button> start a new session> create a new audio track> make sure the correct inputs are selected(go to the mixer view and click on the input for the track, if you're using the spdif input make sure it's selected here, same if you're using the analog inputs)> arm the track> hit record on the transport bar(or just hit F12)> push play on the MPC> PT should record your music now> to montior the playback turn the input/playback knob all the way to the right.
