Connecting a PA5X to a Nautilus via U.S.B. Midi

[chelsea4023]

Hi,
I was hoping one of the Forum Members might be able to help with a USB midi problem I am having.

I have connected up a PA5X to a Nautilus 88. PA5X Master, Nautilus 88 Slave.

The PA5X Host 1 R USB Port is connected to the Nautilus USB B Port.
The PA5X is set to MIDI Channel 1 and I have set the Nautilus 88 Global Channel to 3. Local Control on the Nautilus 88 is set to off. The PA5X plays the Upper 1,2 & 3 sections and the Nautilus 88 plays the lower section of the PA5X.

I have selected exactly the same piano sound for both Upper 1 and lower, the volumes are exactly the same. When I play Upper 1 on the PA5X keyboard it sounds exactly as it should do. When I play the same sound on lower (via the Nautilus 88 keyboard) it sounds different, more like a honky-tonk piano with a slight sustain/decay.
Could somebody who may have had a similar problem please point me in the right direction or suggest what I should be looking out for.
chris