Adding effects to sound i Animate

I try to edit the sound, but no matter what I do, the window for Effect in the Properties-window is not highlighted. And the sync-envelope gives me no obsions either. I click on the layer containing the sound, and under the properties-label I then see the sound-label, but like I say the Effects-window is not working. And when I play back the animation, I hear the sound itself, but if I stop the animation and continue to play from where I stopped, the sound is not coming back. Not before I start the animation from the beginning again. Can anybody help? Yngvar