Soundcard programming

Hello,

Currently I'm programming in Windows for a home project. And I want to write a program to record, process and play audio using my soundcard. When testing everytime I got an errormessage like this: cannot open soundcard since there isn't enough memory.
I'm quite sure I have enough memory. The code I use for opening the soundcard it this:

Code:

bool SoundCardIO::OpenInDevice (void)
/* Description	: open a device for reading */
{
	bool RetVal = TRUE;
	MMRESULT Result;

	TRACE ([OpenInDevice]);

	if (NrOfInDevs > 0)
	{
		Result = waveInOpen (&InDevHandle, DeviceID, &InDevSettings, 0, 0, 
								CALLBACK_NULL);

		if (Result != MMSYSERR_NOERROR)
		{
			TRACE ([OpenInDevice] could not open input device);
			RetVal = FALSE;
#ifdef DEBUG
			WaveFnErrorMessage (Result);			
#endif
		}
	}
	else
	{
		TRACE ([OpenInDevice] no input devices available);
		RetVal = FALSE;
	}
	
	return RetVal;
}

Have I forgotten something? By the way, I use Windows 98.