Version thumb doesn't exist!

[greg]

Uploading files works great, but I keep getting ("Version thumb
doesn't exist!") when I try to insert it into the view...any idea what
might be causing this error?

Also, images are saved in a tmp direct, but kept at the same size...

My avatar_uploader.rb file looks like this:

class AvatarUploader < CarrierWave::Uploader::Base
include CarrierWave::RMagick
storage :file
def store_dir
"uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
end
version :thumb do
process :resize_to_limit => [200, 200]
end
My view has the following:

<% for image in @posts %>
<%= image_tag image.avatar_url(:thumb) if image.avatar? %>
<%= image.title %>
<% end %>
When I don't include (:thumb), I see the full images...but when I do
include the (:thumb), I get the following error:

Version thumb doesn't exist!
I can see that a tmp directory was created, but images not resized...I
have imagemagick and rmagick installed...

Thank you