Andrew, Thanks for your assistance.
I've checked all the various menus you mentioned, and all appears to be as it should.
My keyboard is an Edirol MIDI keybiard Controller PCR-M1. I'm using it with a laptop, connected through USB port. I also have Sibelius 6 on this laptop and the Edirol works perfectly with that. But maybe Sibelius is causing some conflict??
I have set the keyboard to channel 5, as suggested earlier, concerned that it might then confuse Sibelius, but that still works.
?????
Sue