Yamaha DTXpress/DTXplorer/DTXtreme

You do have to concern yourself if power (sometimes/usually Pin9) is 
being utilized somehow.  Laptops will only output about 3.3V from 
this pin, whereas Desktops will typically put out 5V (sometimes 
higher) and with more umph (current capability to power devices).  
It's possible that the internal circuitry is "keying" off it to 
acert the function.  

I've actually manufactured my own cables with a wall-mount 
transformer plug to give me a hearty 5V to power the circuitry 
within the device to be communicated with.

Good luck.

Bill