Hi, as mgasparr mentioned above, the trick is not to include / after : in the tftp-server statement. You get a complain from CLI, but still works. If you want to even avoid the error message, try:
tftp-server flash:/Desktops/320x212x12/CiscoFountain.png alias Desktops/320x212x12/CiscoFountain.png
Hope this helps, please rate post if it does!