[GraemeJ]

I believe I tried the method you described, and I could not get it to work on this particular brand of tablet. 

Yes, this seems to a be fundamental and all-too-common problem with Android tablets.  No two ever seem to be quite the same.  I have two tablets that are supposed to be able to cast the screen to my TV - one does, the other doesn't.  Similarly, I have three tablets with BT4, but my pedal will only talk to two of them. 

IBM got it right when they drew up the original specifications for the PC - manufacturers had a fairly rigid set of 'rules' to follow, which resulted in all PC's being basically the same, no matter who you bought one from.  I think Google were far too lax in allowing so much latitude in the implementation of the basic OS - which is why we all experience different solutions to the same problem.