I got your back on this one Wesley...
and this is based on the identical problem I had last year with my XC600, mine was so bad I couldnt run down a hard packed trail (but I created my own problem)
First let make sure I am on the same page, and these other guys will also better understand. for the sake of understanding, the sled is sitting in the back yard on a nice 10 inch base of snow, nothing is frozen to the ground, and mechanically under the hood everything is fine.
You start the sled, let it warm up, you climb on and hit the gas, the track spins, shoots a roost of snow and the rear of the sled sinks to the grass and the sled never moves an inch.
You have a rear suspension problem !! been there, done that, bought the Tee shirt...
Now, let me ask you a few questions, and I'll also through in some answers to fix your problem.
I am assuming this thing is an Xtra 10, was it ok last year? or did you just get the sled? Have you done any work to the rear suspension? Made any adjustments to the rear suspension?
In a nutshell what your sled is doing is coupling the rear to the front suspension arms just from sitting on the sled, this could be caused from a maladjustment, or pivot points in the rear suspension corroded and frozen. i did a lot of research on this last year trying to get my sled to ride better. rear to front coupling puts a ton of weight on the ski's, and only uses about the last 1/4 of the rear of the track to move the sled, so it digs a trench and sits there. Arctic Cats around the same year did not use any kind of a stop behind the scissor arm, thats why cats do a wheelie so good.
Here is what I would do assuming you just got the sled, or havent done anything to the rear suspension. Pull the skid frame out of the sled, pop the shocks loose and make sure all the pivot points are moving free, if not, get them free'd up.
Next, look at the front limiter straps, they are adjusted by a long bolt, you should have about half an inch of threads showing from the nut, to the tip of the threads. Plus or minus 1/4 inch or so is ok.
Now look at the rear scissor stop blocks (with the springs and shock installed) there should be a gap between both the front and rear scissor stop block and the scissor arm. (if the rear block is touching, or very close to touching, that one is your "wont move" problem) these blocks have 4 sides, each side will change that gap. There are also 2 possible bolt holes you can bolt the blocks to the rails with. Look under the hood on the clutch guard, there should be a picture and basic settings where these blocks would be set at from the factory. Just using the factory settings will get the front end up and the sled moving just fine!
Hope this helps
JR