Problem OrbiterSound 4.0 PlayVesselWave fails, depending on whether an MFD has been up or not

[kuddel]

Hi,

I've come to a problem that is very strange (at least to me ):

I have an MFD which calls

orbiterSoundId = ConnectToOrbiterSoundDLL(vessel->GetHandle());

in its constructor.

After some button pressing etc. a 'Play' method does basically something like this:

if (!IsPlaying(orbiterSoundId, wavNumber))
{
  RequestLoadVesselWave(orbiterSoundId, wavNumber,
    "Sound\\ComMFD\\icao\\ping.wav", INTERNAL_ONLY);
  PlayVesselWave(orbiterSoundId, wavNumber);
}

Everything works perfectly if the MFD is up on startup.
But when I start with no MFD up and select it at runtime [PWR],[SEL],..
PlayVesselWave() returns 0 (zero) a.k.a. FAIL

All return values of any other OrbiterSound calls are the same.

The OrbiterSound_Log.txt also does not reveal any further infos:

Working (MFD up on start):

********************************************************
OrbiterSound 4.0 (3D) Build Nov 20 2012 01:00
********************************************************

Orbiter version: 100830
Advanced OrbiterSound settings: (Edit: 'Sound/cfg/Editable_Advanced_Configuration.cfg')
-------------------------------
Primary buffer            22050hz 16bits  (default 22050/16)
DopplerFactor            1.00        (default 1.00)
VaccumAttenuationFactor        1.00        (default 1.00)
SoundDistanceFactor        1.00        (default 1.00)
MaxSoundProcessPerSecond    60        (default 60)
MaxAnimCheckPerFrame        10        (default 10)
PlayWhenOrbiterInBackground    false        (default false)
WriteInLogAllLoadedSound    false        (default false)
-------------------------------

Orbiter directory:  C:\Program Files (x86)\Orbiter\OrbiterSound40\
Listing planets winds and bases sounds:
  6 planet wind sound found
  4 bases sound found
Passed initModule - Ok
[COLOR="Lime"]Vessel STS-101 requested an ID, returned= 0 OK[/COLOR] 
Attempting RenderViewport initialisation...
Attempting GetStartValue initialisation...
Passed GetStartValue - Ok
Initialising directsound...
   Sound hardware capabilities: Driver is not certified.
   Maximum hardware mixing buffers: 1.
   Maximum hardware 3D buffers: 0. 
   Speaker configuration: stereo with wide (arc of 20 deg.) geometry  
   Attempt to create Primary buffer: 22050hz 16bits 3d: yes 
   3D primary buffer initialised OK
directsound initialised - OK
Passed RenderViewport - Ok
Attempting Mp3 initialisation...
M3U list found attempting loading it.
MP3 found in playlist =  1
Mp3 initialised - Ok
Focus changed attempting to load vessel wave
Info: Sound config found for class: Atlantis. 20 parameters set.
Focus changed load vessel wave - OK
Attempting to close viewport...
Attempting to kill DirectSound...
-------------------------------
Wav files Statistics:
---------------------
Nbr of wav loaded during simulation: 50
Nbr of wav re-used from memory: 0 (not loaded from disk so not counted in wav loaded)
Max nbr of wav in memory in same time: 45
Nbr of wav failed to load: 0
Nbr of wav not unloaded at exit: 0
------------------------------- 
DirectSound killed - OK
Passed CloseRenderViewport - Ok
Exited to Orbiter Launchpad - OK

Passed ExitModule - Ok

Not working (MFD instantiated at runtime):

********************************************************
OrbiterSound 4.0 (3D) Build Nov 20 2012 01:00
********************************************************

Orbiter version: 100830
Advanced OrbiterSound settings: (Edit: 'Sound/cfg/Editable_Advanced_Configuration.cfg')
-------------------------------
Primary buffer            22050hz 16bits  (default 22050/16)
DopplerFactor            1.00        (default 1.00)
VaccumAttenuationFactor        1.00        (default 1.00)
SoundDistanceFactor        1.00        (default 1.00)
MaxSoundProcessPerSecond    60        (default 60)
MaxAnimCheckPerFrame        10        (default 10)
PlayWhenOrbiterInBackground    false        (default false)
WriteInLogAllLoadedSound    false        (default false)
-------------------------------

Orbiter directory:  C:\Program Files (x86)\Orbiter\OrbiterSound40\
Listing planets winds and bases sounds:
  6 planet wind sound found
  4 bases sound found
Passed initModule - Ok
Attempting RenderViewport initialisation...
Attempting GetStartValue initialisation...
Passed GetStartValue - Ok
Initialising directsound...
   Sound hardware capabilities: Driver is not certified.
   Maximum hardware mixing buffers: 1.
   Maximum hardware 3D buffers: 0. 
   Speaker configuration: stereo with wide (arc of 20 deg.) geometry  
   Attempt to create Primary buffer: 22050hz 16bits 3d: yes 
   3D primary buffer initialised OK
directsound initialised - OK
Passed RenderViewport - Ok
Attempting Mp3 initialisation...
M3U list found attempting loading it.
MP3 found in playlist =  1
Mp3 initialised - Ok
Focus changed attempting to load vessel wave
Info: Sound config found for class: Atlantis. 20 parameters set.
Focus changed load vessel wave - OK
[COLOR="Lime"]Vessel STS-101 requested an ID, returned= 0 OK[/COLOR] 
Attempting to close viewport...
Attempting to kill DirectSound...
-------------------------------
Wav files Statistics:
---------------------
Nbr of wav loaded during simulation: 50
Nbr of wav re-used from memory: 0 (not loaded from disk so not counted in wav loaded)
Max nbr of wav in memory in same time: 45
Nbr of wav failed to load: 0
Nbr of wav not unloaded at exit: 0
------------------------------- 
DirectSound killed - OK
Passed CloseRenderViewport - Ok
Exited to Orbiter Launchpad - OK

Passed ExitModule - Ok

Can anyone giving me some hints?

I have also tried to call ConnectToOrbiterSoundDLL at some other times (InitModule, 1st opcPostStep, ...) but nothing changed that behaviour.
Also using PlayVesselRadioExclusiveWave instead of PlayVesselWave made no difference.