[Fizzlemizz]

It displays fine. A green box means one of: something wrong with the image, an incorrect path to the image or you didn't completely exit the game before pasting and then restart and try to display the image.

The game caches file names when it starts and won't recognise any new files until you exit and re-start. Once it knows a file exists, you can modify it and then update the changes with /reload.