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 NavigatorTM, Press the Shift key while clicking the Reload button to ensure that the cache is not used. If the images are already in the cache, this action does not always force the client to fetch images from the source.
You might also want to disable the server cache using the cache-init SAF.
Examine the access log and error log to help with debugging.