Images (aerial, tiff) and mosaic data set are all contained in folders that are registered and validated data stores. arcgis server domain account has full permissions on all folders, sub folders. Image server extension is activated.
Image service publishes successfully without needing to copy data to the server - tested both map and image services.
The images and overviews all show up as the checkerboard indicating the server does not have access to the files.
I would be grateful if anyone could suggest something that I might be missing? I should also mention that the image server extension is a 60 day trail so I am not eligible to use the technical support service.