Hmmm...I can't explain it. Do you get the same output every time you press the key? I'm wondering if it's a hardware thing now. Or maybe Casio has a "MIDI-esque" output that doesn't meet the standard?
--
The Rugged Circuits Yellowjacket: 802.11 WiFi module with ATmega328P microcontroller, only 1.6" x 1.2", bootloader