Trouble with uploading images to the IPad pro 2nd generation for app submission

I am trying to upload and submit a screenshot for the iPad pro 2 generation 12.9 inch so that i can submit my app for review. The dimensions that I've used are from the screen shot specification app store, (iPad Pro (2nd generation) 2048 x 2732 pixels (portrait) 2732 x 2048 pixels (landscape.) When I attempt to upload the screen shots it keeps telling me that the dimension are wrong. The sizes that I've used with no success are 2048 x 2732, and 1536 x 2048.