iphone : getting error of "_AudioSessionSetProperty" while playing recording

i am getting error of ,

Undefined symbols for architecture i386:
  "_AudioSessionSetProperty", referenced from

whil开发者_StackOverflowe playing my recording.I have included,

#import <AVFoundation/AVFoundation.h>
#import <CoreAudio/CoreAudioTypes.h>
#import <AudioToolbox/AudioToolbox.h>

frameworks and its header files. what is missing?

did u include the AudioToolbox framework to the application?