Alliance and Horde on same server

Hey guys! I'm pretty new to Warmane and was wondering if it is possible for me create both an Alliance character and a Horde character on the same server. I was trying to do as such but it was coming up as an error so I'm getting the idea that this may not be possible.

Edit: I forgot to mention that I'm playing on the Deathwing server.

Edit 2: ISSUE SOLVED! I don't know what the issue was really but I am able to create one on each side with no problem now. I'd delete this post but i'm not sure how lol

Playing on Ragnaros, but never had any problems with that.

You likely downloaded the Warlords of Draenor models and selected a hairstyle that doesn't exist in Wrath of the Lich King. To fix you need change your hair, skin, features, etc until it allows you to make a character.

I really wish they would switch the position of the Warlords model patch with the standard client, it would reduce these kinds of threads, among others, significantly. That or add a large disclaimer before downloading.