JSON API Connector Issues

So I’m posting an image with a caption to a Facebook page. It works when I test it with all the same info on Facebook’s Graph API Explorer, and it even worked on Bubble when I didn’t use the JSON but instead just added parameter form fields. However, when I try use this JSON code it doesn’t work. I have added the Content-Type to the shared header of the API call. Any idea what I might be doing wrong?

It seems to be telling you to send a file. And you’re not sending a file. Are you missing a file parameter?