If you are stabilizing the footage then removing the stabilization as I did in the short tutorial you do not apply tracking info to anything, you add a null then use an expression to tie the null position to the anchor point of the tracked footage then you make the null the parent of the sun and the tracked footage. This removes the stabilization from the footage and adds the movement to the sun layer.
Take a very careful look at the tutorial that I posted. This is a very simple procedure.