[ronlomax]

I'm a little confused - you said you connected to the Google library, but just switching to that library won't connect you to the keyboard. Once you switch to that library, you need to see input/output ports show up, and then you need to tap on them to connect to the keyboard. If you don't see input/output ports, the keyboard isn't being recognized. In that case, you only have a few options:

1) Try a different cable
2) Put an MIDI-class compliant device between the tablet and the keyboard such as the Roland UM-ONE or the mio2 to see if this allows your tablet to communicate
3) If your keyboard supports MIDI over bluetooth, you could try that, or you could get a MIDI over bluetooth adapter

If you want a sanity check, you could try installing another MIDI app to see if it recognizes the keyboard, although I imagine the result wouldn't be any different. 

Normally when a keyboard is connected over MIDI, if you drag down from the top of the screen, there are options for how to handle the USB connection. What is this currently set to? If you changed it to something like MIDI, does that have any impact? If you don't see any notification about the USB connection at all, that would obviously be a red flag.

Mike

Hi Mike   I think I am confusing you. With the default library the screen space below the option was totally blank. Whwn I switched to the Google library, the screen space below showed just the headers for input and output. It did not list any ports. The link icon on the song edit/midi page only showed when the google library was selected.
I have tried the connection over both bluetooth and with a midi to USB device. Nothing. I have changed the cable, but it made no difference. If I connect a laptop or even a usb key to the keyboard, I get a connection message on the keyboard screen. I am not getting that.
There is no notification on the tablet about a usb connection. If I plug the tablet into a laptop, it is not recognised by the laptop. It does not show in windows explorer, and the message on the tablet is 'Android System - charging over USB'
I believe the problem has to be with the tablet, so tomorrow, rather than waste any more of your time,  I intend to get a Samsung Tab A, and try again. I will let you know the result.
Thanks for all your help. 
Ron