If you're using aYamaha wireless Midi Adapter P/n MD-BT01 READ THIS, if not disregard. FWIW - I have this bluetooth adapter which plugs into both the MIDI IN and the MIDI OUT ports. It getsit'power frpm the keyboard MIDI BUS. I had trouble with it not working with my Yamaha S80 and Motif ES. However it works fine with my Casio PX-5S. I believe my MB-BT01 was not getting bus power from the 2 older keyboards (but not sure). Here is some info quoted from another user site:
"The two important "issues" for you to be aware of before buying the MD-BT01 are: (1) It requires MIDI power and both the IN and OUT jacks; and (2) iOS Bluetooth doesn't recognize it natively, so Yamaha has engineered a software workaround. The device runs off the power of the hardware you plug it into IF your device offers MIDI power. There are more units than you'd think that do not have MIDI power. This would include all of the Korg Volca series, which only has a MIDI in jack. By contrast, the Korg Minilogue and Roland Boutique series do provide MIDI power to run the device.
Once powered up, you can't just go to your Bluetooth menu in "Settings" and find the MD-BT01. You have download Yamaha's utility app to find the device and connect to it. You can also rename the unit or do firmware updates from that utility. As several reviewers have pointed out, I think you also have to identify it as a MIDI destination in an app that supports it. There are several of these, but I found that if I skipped this step, I couldn't just load up a sequencer app (like Inifinite Looper or Xequence) and make the connection. But once it works, it generally works.
I should point out that my primary concern prior to buying the device - latency - really isn't much of an issue at all. The latency seems pretty minimal, and if you're just using the MIDI connection for sequencing or to mess with control parameters on a synth, it's basically a non-factor anyway. "
Good luck! Don aka B3