I cannot speak for Krhyde but I do know that if your site is way off level it may fault out. I think, but not sure, that if you are off by 4* or more, that is the cut off. But...you will still be able to level. What you would need to do is cheat a little bit by manually raising the low side and then hitting "Auto Level".
I do know one guy that stores his next to his garage and the site is way off level. His Landmark sits all winter with two tires off the ground.
Peace
Dave