How to control playing the seleted animation of a model?

I have loaded a dae type model,and the return of getAnimationCount() is 6.It means the model has 6 animation .Now I want to play someone,for example 1 index.In the touchDown(),like this:
void ofApp::touchDown(ofTouchEventArgs & touch){
model.stopAllAnimations();
model.getAnimation(1).play();
}
but it runs same with model.getAnimation(0).play();

void ofApp::touchDown(ofTouchEventArgs & touch){
model.stopAllAnimations();
model.getAnimation(0).play();
}
.So why?Is there something wrong?How to control the seleted animation of a model?