Problems assigning track inputs in SONAR Artist

Hello all. I recently set up my home studio with a Tascam US-1800 16-input interface. Initially, I was using a *trial* version of Sonar X3, which was working perfectly for me. My trial period expired so I decided to purchase the only thing I could afford, Sonar Artist. Now, in X3, I was able to assign all 16 inputs to whichever channel I wanted them to record to. In Artist, all my individual inputs don't show up. All that shows is "Tascam line in" rather than "Tascam mic 1, mic 2, etc." I've checked all the drivers. Everything is EXACTLY how I had it set in X3. Why is Sonar Artist not recognizing all my inputs? Is it not capable of multitrack recording? If this is the case then they were very misleading on the advertising. Any help here would be much appreciated. I'd hate to think I finally bought Sonar because I thought it was a good product, and it's not even going to do what I bought it for. Thanks!