Hi there,
So, Are you using the HID device LIB for it?
Check out the MIdi examples to get an example, sounds like your close so Stay with it, Post up the code and others can comment, Use the code tags above “</>” paste it in there.
You get better help and it’s easier to read and test. 
HTH
GL 
PJ 
What OS? to show up as a BLE device Pairable?