There are many possible causes for this problem. However, the most common is attempting to upload a too large image file. By their nature, Icons are small images of a few tens of pixels. Larege image files, a representative product photo, for example, should be embedded in the category description text.
If you are truly tring to upload a small, icon image, please submit a support ticket with a complete description of the problem. Include your web site url, category name, and attach a copy of the icon image you are attempting to upload. One of our technicians will respond as quickly as possible.
Remember you must login to the Client Area before you can submit a support ticket.