Image Cache not displaying?

Per the help text at the top of the fieldset:

Note that only file fields that use the "Image" widget type support ImageCache configuration options.

You have to switch the widget to "Image" instead of "File" or whatever other widget you're using.

You need to download and enable Image field module (drupal.org/project/imagefield) and then change the widget type to "image" from "file upload" in node-type manage fields.

If you have already created the "file" field for uploading images then you need to click on "configure" of the file field and then click on "change basic informaiton" and then change "file upload" to "image" and then go to manage fields and set imagecache(s) in "html filter"