Just had a couple of the Venue Pro tablets arrive. They are not sold with 8.1 pro, they are only sold with 8.1. I am on a domain and need to join the Venue to the domain. How do I join the 8.1 machine to the domain without whipping out a cedit card and purchasing the pro pack. We have an enterprise agreement and a KMS server. I have tried all the keys using the "I already have a key" process in 8.1 and they dont work.