Summary renders as [body-summary]

I'm trying to use my content summaries (AKA teasers) in a view. To do that, I selected "content: Body", and from its settings page, I went to the "Rewrite results" section, checked the "Rewrite the output of this field" check box, and put "[body-summary]" in the text field. However, when I look at my view, it doesn't display the actual summary, instead it renders as [body-summary]. Anybody know why this is happening? and if I'm doing something wrong?