No Cellular Hotspot?
I have iPad Mini, model A1455 (Wi-Fi, Cellular), but it doesn't have a Cellular and Personal Hotspot option in the settings. Why?
iPad Mini, iOS 8.1.3, Model A1455
The message you're getting is pretty clear - you need to contact your carrier about this. They have not enabled Personal Hotspot for your iPad's account.
~Lyssa