Yamaha DTXpress/DTXplorer/DTXtreme

Hi, 

Has anyone else tried controlling the DTXpress brain from their computer
via the midi port.

My computer / sequencer software will receive midi from the brain no
problem but when I try to transmit midi to the brain to trigger the
sounds I get an error on the brain's display - "MIDI FRAMING ERROR"

Not being a MIDI expert I haven't got a clue what this is ?

Can anyone out there help ?

Thanks

Andy