Getting error: Unknown tag 'pullquote'

[kenirwin]

Hi folks,

I'm just trying out this gem, and when I try building the site with a pullquote, I get this error:
Error: Liquid syntax error (line 7): Unknown tag 'pullquote'

Do you know what might cause this? It appears that the gem is installed.

Here's the code that's causing the error.

{% pullquote %}
This paragraph is going to have to be long enough to bother with a pullquote. Therefore, it needs to be good and long. It doesn't really have to say anything, but it does have to take its time about it. So let's see what we can do about that. {" It doesn't take much, does it? "} And that is really the whole point.
{% endpullquote %}

Any ideas? I'm not sure how to go about troubleshooting this. Thanks!