Greetings CountMountjoy,
Welcome to Apple Support Communities.
It sounds like you’re running into an issue upgrading iOS on your iPad with Retina display, iTunes is displaying a few different alert messages. I can imagine this would be frustrating. Take a look at the article linked below, it provides a lot of great information and troubleshooting suggestions that will resolve most issues like this.
Resolve network errors
Related errors: 17, 1004, 1013, 1638, 3014, 3194, 3000, 3002, 3004, 3013, 3014, 3015, 3194, 3200, or "There was a problem downloading the software," or say the "device isn't eligible for the requested build.". These alerts mean that your computer is either having difficulty contacting the Apple update server or communicating with your device.
Check your computer for software or settings that might cause communication issues between your computer and Apple or between your computer and your device.
Check your security software
Related errors: 2, 4, 6, 9, 1000, 1611, 9006. Sometimes security software can prevent your device from communicating with either the Apple update server or with your device.
Check your security software and settings to make sure that they aren't preventing a connection to the Apple servers.
I hope this helps.
-Jason
