How to get sound out of a moonsound?

I've added the wait, and I can see in de debugger that for a couple of runs the LD flag is set so that seems to be working. But even after waiting until the LD flag is back to zero I still hear no sound at all. I am testing this in OpenMSX on the Boosted MSX 2 EN machine so no 7Mhz or Turbo R running which seem to need more waits added. I have no clue what could be the problem right now.

I've added the complete code here.

BDOS: EQU 0x05
_STROUT:	EQU 0x09

    org 100h
START:
    call MS_DETECT
    jp nz, detected
    ld de, TXT_MS_NOT_FOUND
    call PUTSTR
    ret

detected:
    ld de, TXT_MS_FOUND
    call PUTSTR

; Init Moonsound
    ; Enable the wave register and extra status bit
    ld a, 5
    ld b, 3
    call MS_WRITE_FM2_REG

    ; Use instruments from ROM ??
    ld a, 2
    ld b, 00010000b
    call MS_WRITE_WAVE

; Set wave 300 on channel 0
    ld a, 20h
    ld b, 1
    call MS_WRITE_WAVE
    ld a, 08h
    ld b, 44
    call MS_WRITE_WAVE
    call MS_WAIT_WAVE

 ; set octave 1, fnum 0 (aka 44.1Khz) + wave 1 on channel 0
    ld a,38h
    ld b, 00010000b  ; 4 bits octave, 4 bits fnum
    call MS_WRITE_WAVE
 ; Set volume
    ld a, 50h
    ld b, 33
    call MS_WRITE_WAVE  
 ; Key on (1), damp off (1) , reset LFO (1), output to channel (1), panning (4)
    ld a, 68h
    ld b, 10010000b;
    call MS_WRITE_WAVE
 ; Key off (1), damp off (1) , reset LFO (1), output to channel (1), panning (4)
    ;ld a, 68h
    ;ld b, 00010000b 
    ;call MS_WRITE_WAVE
    ret

; Moonsound routines etc
MS_WAVE_REG:        EQU 07Eh
MS_WAVE_DATA:       EQU 07Fh
MS_FM_BANK1_REG:    EQU 0C4h
MS_FM_DATA:         EQU 0C5h
MS_FM_BANK2_REG:    EQU 0C6h
MS_STATUS_REG:      EQU 0C4h

; Check if there is a Moonsound
; Returns:
;   NZ if detected
;   Z if not detected
MS_DETECT:
    in  a, (MS_STATUS_REG)
    cp 0xFF
    ret

; Initialize / reset the moonsound
MS_INIT:
    ; Enable the wave register and extra status bit
    ld a, 5
    ld b, 3
    call MS_WRITE_FM2_REG

    ; Use instruments from ROM ??
    ld a, 2
    ld b, 00010000b
    call MS_WRITE_WAVE

    ret

; Write to register in FM2
; Input:
;   A = Register
;   B = Value
MS_WRITE_FM2_REG
    out (MS_FM_BANK2_REG), a
    ld a,d  ; wait 56 / 33.87 µs
    ld a,b
    out (MS_FM_DATA), a
    ret

; Write to register in Wave
; Input:
;   A = Register
;   B = Value
MS_WRITE_WAVE
    out (MS_WAVE_REG), a
    cp (ix)  ; wait 88 / 33.87 µs (9.3 bus cycles, but 9 works)
    ld a,b
    out (MS_WAVE_DATA), a
    ret

MS_WAIT_WAVE:
    in  a, (MS_STATUS_REG)
    and 2
    jp nz, MS_WAIT_WAVE
    ret 

PUTSTR:
	PUSH AF
	PUSH BC
	PUSH DE
	PUSH HL
	LD C,_STROUT
	CALL BDOS
	POP HL
	POP DE
	POP BC
	POP AF
	RET

TXT_MS_FOUND:	db "Moonsound detected. Playing a sound?$"
TXT_MS_NOT_FOUND:	db "Moonsound not detected.$"

I found the problem. But now I'm not sure if its the documentation (opl4tech.txt) or openMSX being wrond here, my guess is the documentation.

+ 68H-7FH CH

  Output channel:            +-----+----+----+----+----+----+----+----+----+
                             |     | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 |
  0: Outputs to MIX          | 68- +----+----+----+----+----+----+----+----+
                             | 7FH |              | CH |                   |
  1: Outputs to PCM-EXT      +-----+--------------+----+-------------------+

  For the MoonSound all channels need to be set to PCM-EXT.

It states that D4 needs to be 1 to set is to PCM-ext, and that for all channels this must be set. I changed this to zero with the code above and I got a sound.

So

; Key on (1), damp off (1) , reset LFO (1), output to channel (1), panning (4)
    ld a, 68h
    ld b, 10010000b;
    call MS_WRITE_WAVE

became

; Key on (1), damp off (1) , reset LFO (1), output to channel (1), panning (4)
    ld a, 68h
    ld b, 10000000b;
    call MS_WRITE_WAVE

Correction . MIX = PCM+FM