That sounds like it failed to load the image file for the barcode. If you have the 12 digit Disney Reservation Number above that box, I think you'll be OK. That number is all you need to link them on MDE, at least.
Thanks! I had opened the email and printed the confirmation from my iPad. When I checked the email on my laptop just now, the barcode was there!Same thing happened to me today when I opened it on my iphone. On my, PC, the bar code showed up. I just successfully linked them to my MDE this morning with the 10:15 email they sent me.