I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.
You can also use the “preformatted text” tool in the editor (</>) to add backticks around text.
By normal developer standards, you haven’t done anything wrong.
It’s just that space you put into the placeholder.
It should be just one space between photo URL.
The script that runs to detect if you have done it correctly is looking for you to follow the instructions exactly, so when you changed that, it has broken its ability to detect your code.
(If you get stuck like this in future then consider pressing the “Reset All Code” and doing it again)