the filename of this image has a forward slash in it. I would try removing that first, special characters in filenames often cause issues.
Otherwise:
- check the file is in the right place as the other images and the url path to it is correct.
- check that your list of images has a comma at the end of every line except the final line.
- check the ID you give it starts with BG_ and that you call the correct ID in the script.
if all of them check out, bring up the developer tools when you have the game in browser (f12), go to console, see if it spits out an error.
