Audio Scrub Preview Not Working....Why?

I used to use the scrub by pushing the right arrow one stroke and I could hear the corresponding single frame sound. This was totally useful when finding the kicks or snares of a song, so that I could sync it up with action in the video. Now when I click the forward or backward key, the player head moves forward/backward, but I cannot hear any sound. If I push play, the sound plays back totally fine. Basically, the scrub preview is not working. I didn't change any settings. I switched the audio driver, changed it back, reset the computer numerous times, but no luck.

Any advice?

Timeline>Audio Scrubbing.

Also Shift+S shortcut.