Regarding iPad, this is from the summary page for those eBooks:
Note: Not compatible with Mac and Blackberry Clients
I'm afraid I don't know why they have compatibility issues with Mac Clients but there is a good chance this is what the problem is.
Regarding samples, it doesn't surprise me those would download fine. They are a different eBook, very small, and the few I have looked at are DRM free.
I agree, the ipad is not a Mac client. I've had the ipad app ever since it was announced on the B&N website and have had no problems in the past with downloading my entire library and on the same day the app downloaded another book at the same time. I think it has something to do with the fact that I downloaded the sample first.
I was able to download the books via wi-fi at home but there's no reason why it didn't download with the 3G.
Thanks for all of your answers and trying to help, I appreciate it.
Karen / lilk13