Anxious to contribute some of your hard-earned money? We probably won't refuse!
Not so anxious? That's cool, we're still friends.
Your icons are eventually removed from our server! Every so often - often once per week - a script is called which clears out all existing icons. We simply don't have the server space to do anything else.
Your image files might be too big! When analyzing your image if the explicit memory limit is exceeded, your file might not be converted.
But just resize your image, and try again.