Perhaps your problem is that the DW-6000 is sending data on a single MIDI channel and your XP-50 PERFORMANCE has different PARTS with different receiving MIDI channels assigned to them.
The XP-50 will play only the PARTS which are assigned the same MIDI channel your DW-6000 is set to transmit.
If you want to play simultaneously several sounds of the PERFORMANCE, you have to activate several PARTS and assign them the same MIDI channel the DW-6000 is set to transmit.
You can assign each part the whole keyboard range to assign all the PERFORMANCE sounds to the DW-6000 keyboard, or assign different keyboard ranges to different PARTS if you want to 'split' your DW-6000 keyboard.
I hope this solve your problem.
maubeda@mail.fujitsu.es