It is required that you upload an image for your image advertisement.

Drupal 7.39, Ad 7.x-1.x-dev (September 18, 2015)
I'm getting this error even though I have uploaded an image. I create a new image ad, upload an image as a file attachement, click save and it won't create the node, throwing the error message in the title. I look in the directory where the image should be saved and the image is in the directory so the upload is definitely happening. Not sure why I'm getting this error, but I cannot create any image ads due to it.

The submodules I have enabled are: Ad, Ad Weight Probability & Image Ad.