I'm totally, completely baffled!

I uploaded 2 novels to Kindle and had absolutely no trouble with uploading the cover.

However, carefully following the guidelines for Nook, I was only able to upload the cover for Follow The Raven. Using the exact same configuring, I tried to upload the one for Blood in the Meadows - and it wouldn't take!

Of course, nobody in the B&N staff seems inclined to respond to my questions so I'm forced to seek advise here.

Thanks in advance.