broHey.
Make sure:
- Upload the image in your c_images folder in SWF's folder. Create the folder room_ads and put it there.
- Make sure you remove the ads.domain from external variables / override_variables
- Make sure the link in-client on the ads_background is like /swf/c_images/room_ads/image.png and not http:// or https:// in front of it.
- Try developer console to see if it can reach the image.
Let me know if this worked.