Lautstärke auf XP ändern mit delphi

[Noobinator]

ich habe diesen Code jetzt in meine Unit eingebunden
[code=delphi]uses
MMSystem;

function GetMasterMute(
Mixer: hMixerObj;
var Control: TMixerControl): MMResult;
// Returns True on success
var
Line: TMixerLine;
Controls: TMixerLineControls;
begin
ZeroMemory(@Line, SizeOf(Line));
Line.cbStruct := SizeOf(Line);
Line.dwComponentType := MIXERLINE_COMPONENTTYPE_DST_SPEAKERS;
Result := mixerGetLineInfo(Mixer, @Line,
MIXER_GETLINEINFOF_COMPONENTTYPE);
if Result = MMSYSERR_NOERROR then
begin
ZeroMemory(@Controls, SizeOf(Controls));
Controls.cbStruct := SizeOf(Controls);
Controls.dwLineID := Line.dwLineID;
Controls.cControls := 1;
Controls.dwControlType := MIXERCONTROL_CONTROLTYPE_MUTE;
Controls.cbmxctrl := SizeOf(Control);
Controls.pamxctrl := @Control;
Result := mixerGetLineControls(Mixer, @Controls,
MIXER_GETLINECONTROLSF_ONEBYTYPE);
end;
end;

procedure SetMasterMuteValue(
Mixer: hMixerObj;
Value: Boolean);
var
MasterMute: TMixerControl;
Details: TMixerControlDetails;
BoolDetails: TMixerControlDetailsBoolean;
Code: MMResult;
begin
Code := GetMasterMute(0, MasterMute);
if Code = MMSYSERR_NOERROR then
begin
with Details do
begin
cbStruct := SizeOf(Details);
dwControlID := MasterMute.dwControlID;
cChannels := 1;
cMultipleItems := 0;
cbDetails := SizeOf(BoolDetails);
paDetails := @BoolDetails;
end;
LongBool(BoolDetails.fValue) := Value;
Code := mixerSetControlDetails(0, @Details,
MIXER_SETCONTROLDETAILSF_VALUE);
end;
if Code <> MMSYSERR_NOERROR then
raise Exception.CreateFmt('SetMasterMuteValue failure, '+
'multimedia system error #%d',

Code:

);
end;

und das ins Formcreate geschrieben:

SetMasterMuteValue(100,true); nur irgendwie geht das doch nicht.
woran liegt das?

ok habe es Geschafft^^ mein Fehler lag hier:

SetMasterMuteValue(100,false);/false statt true danke euch