IPad 2 will not update from version 4.3.5 (8L1).

I got an iPad 2 from work and it will not update from version 4.3.5. There isn't even a software update option in settings. I have reset and erased it a few times, and still no update option. I have plugged it into my computer to try to update it that way and every time iTunes prompts me to download and update the latest version, it loads for a few seconds and then I get an iTunes message that says "The IPad software update server could not be contacted. Make sure your network settings are correct and your newtwork connection is active, or try again later." the network connection IS active, I can use safari, and I have "tried again later" and still no update. PLEASE HELP!