django-imagekit minimal setup not working

I want to upload image with width 400px and get two other images - 200px and 100px. I googled and django-imagekit looks like it can do this.
So I added imagekit to INSTALLED_APPS and added this to my model:

from imagekit.models import ImageSpecField
from imagekit.processors import ResizeToFit
class Bookmaker(models.Model):
    ...
    logo_large = models.ImageField(upload_to="logo/large")
    logo_medium = ImageSpecField([ResizeToFit(width=200)], source='logo_large', options={'quality': 90})
    logo_small = ImageSpecField([ResizeToFit(width=100)], source='logo_large', options={'quality': 90})

And this is my form:

@staff_member_required
def new(request):
    if request.method == 'POST':
        form = BookmakerForm(request.POST, request.FILES)
        if form.is_valid():
            form.save()
    else:
        form = BookmakerForm()
    template = loader.get_template('bookmaker/new.html')
    context = RequestContext(request, {
        'form': form,
    })
    return HttpResponse(template.render(context))

I've gone through docs but I could not understand how imagekit works. Do I need to setup CACHE in my app? Does it create files physically in MEDIA folder?
Well my setup does not work. When I upload image logo_large, large file is created, but logo_small and logo_medium are not. If I print {{bookmaker.logo_small}} I get media/CACHE/images/logo/large/bookmaker/24d9f99ffdf277ed3fc25e2cf4d37554.jpg, which does not exist (404). Do I need to setup CACHE to make it work?

Hm, it works now. I did not do anything. Probably just takes some time to generate those images (I do not know what it takes to generate images), probably restart ./manage.py runserver is enough.

May be I need to call ./manage.py generateimages after every upload?