Django pipeline does not compress

I just installed the django pipeline in my django application and does not seem to compress my javascript files. It seems to be installed correctly, as the template tags work correctly. I use manage.py collectstatic to compress files. Here is my current configuration. I also created my application for using django-staticfiles for django-pipelined documents since I am using Django 1.3.

 STATIC_ROOT = os.path.join(PROJECT_ROOT, 'site_media', 'static')
 STATIC_URL = '/site_media/static/'
 ADMIN_MEDIA_PREFIX = '/site_media/static/admin/'

 STATICFILES_DIRS = (
    os.path.join(PROJECT_ROOT, "media"),
 )

 STATICFILES_FINDERS = (
    ##Turn these on if using django.contrib.staticfiles
    ##'django.contrib.staticfiles.finders.FileSystemFinder',
    ##'django.contrib.staticfiles.finders.AppDirectoriesFinder',
    ##'django.contrib.staticfiles.finders.DefaultStorageFinder',

    ##Turn these on if using django.contrib.staticfiles
    'staticfiles.finders.FileSystemFinder',
    'staticfiles.finders.AppDirectoriesFinder',
    'staticfiles.finders.DefaultStorageFinder'
 )

 PREREQ_APPS = [
    # Django
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.sites',

    #External
    'south',
    'staticfiles',
    'pipeline',    
 ]


 PIPELINE_YUI_BINARY='/Applications/yuicompressor-2.4.7/build/yuicompress'

 PIPELINE_JS = {
    'site': {
        'source_filenames': (
            'js/libs/ddsmoothmenu.js',
            'js/script.js',
        ),
        'output_filename': 'js/script.min.js',
    }
 }

I'm not sure what I'm missing here, but I'm sure this is something. I do not receive any error messages or anything else, it just does not compress.

Thank you for your help!