UP Audio Core 9.0: No FIFO space !!!

I'm using the "Quartus 10sp1 Web Edition" and the "NIOS II 10 Software Build Tools for Eclipse" to building a program that tests the Audio CODEC on DE2 Board.

I downloaded the "UP avalon audio core" from University IP core ( "ftp://ftp.altera.com/up/pub/University_Program_IP_Cores/90/...") to include into my SPOC. And, this is my software:

#include "altera_up_avalon_audio.h"

int main(void)

{

alt_up_audio_dev * audio_dev;

/* used for audio record/playback */

unsigned int l_buf;

unsigned int r_buf;

// open the audio port

audio_dev = alt_up_audio_open_dev ("/dev/audio");

if ( audio_dev == null)

alt_printf ("error: could not open audio device \n");

else

alt_printf ("opened audio device \n");

/* read and echo audio data */

while(1)

{

int fifospace = alt_up_audio_read_fifo_avail (audio_dev, alt_up_audio_right);

if ( fifospace > 0 ) // check if data is available

{

// read audio buffer

alt_up_audio_read_fifo (audio_dev, &(r_buf), 1, alt_up_audio_right);

alt_up_audio_read_fifo (audio_dev, &(l_buf), 1, alt_up_audio_left);

// write audio buffer

alt_up_audio_write_fifo (audio_dev, &(r_buf), 1, alt_up_audio_right);

alt_up_audio_write_fifo (audio_dev, &(l_buf), 1, alt_up_audio_left);

}

}

}

It's no working, everything is quite.Then, i tesed value of fifospace, always is zero !!!.

It is NO FIFO SPACE ???.

Anybody can help me plz !. Thanks !.