Here are some reasons why this might be happening:
Our system does not allow hosted image URL's for the ad creative. You must upload your ad image using the Browse button and then select the ad image from your computer to upload.
You may be trying to upload a format that is not allowed. At this time, we only the following formats to be uploaded for your ad image: JPG, PNG and GIF.
If you are still having issues uploading your creative, please submit a support ticket and we will be happy to help.
We tend to answer most support tickets during normal business hours: Monday to Friday, 9:00 am to 6:00 pm (EST). However, we're constantly monitoring tickets, and we'll address urgent issues on nights and weekends, too.
Open a Ticket