Logic Express 9 - Apple Loop Audio File Question

I'm running Logic Express 9 on a MacBook Pro. When I pull an Apple Loop Audio File from the Loop Browser area to the Arrange Area, the loop visually clicks into the first 2 bars, as it should. However, when I try to play the loop, no sound comes out of my headphones.

There is sound in my headphones when I play the loop in the Loop Browser area on the right of the screen. So it's not a problem with the headphones, etc.

Is there some setting I need to change to hear the loop after it is pulled over to the Arrange area?

Thanks.