Please help..can not play audio with CMdaAudioPlayerUtility

Hi All

I want to play an audio file wav or mp3 with the use of CMdaAudioPlayerUtility but I don't know why it doesn't play it.
I wrote a class called AudioTest

and in AudioTest.h :

class CAudioTest : public CBase,public MMdaAudioPlayerCallback

.
.

private:
enum TState
{
ENotReady,
EReady,
EPlaying
};

TState iState;

and in AudioTest.cpp:

void CAudioTest::Play()
{
if(iState==EReady)
{
iState=EPlaying;
iMdaPlayer->Play();
}

and for implementation of metthods of MMdaAudioPlayerCallback I wrote like this:

void CAudioTest::MapcInitComplete(TInt aError, const TTimeIntervalMicroSeconds& /*aDuration*/)
{
iState = aError ? ENotReady : EReady;
}

void CAudioTest::MapcPlayComplete(TInt aError)
{
iState = aError ? ENotReady : EReady;
}

the program runs without error but it doesnt play the audio file,and I realizad that I can not enter to if statement in function CAudioTest::Play() and the reason is because CAudioTest::MapcInitComplete(..) is not called,but I have read that it is called automatically,please help me to know that.