Test your SAF by accessing your server from a browser with a URL that triggers your function. For example, if your new SAF is triggered by requests to resources in http://server-name/animations/small, try requesting a valid resource that starts with that URI.
You should disable caching in your browser so that the server is sure to be accessed. In Netscape Navigator you may hold the shift key while clicking the Reload button to ensure that the cache is not used. (Note that the shift-reload trick does not always force the client to fetch images from source if the images are already in the cache.)
You may also wish to disable the server cache using the cache-init SAF.
Examine the access log and error log to help with debugging.