Sorting Expression Assistance

[AnthonyPSH]

I'm new to Qlik and trying to sort summarized totals for groups based on years.  I'm having trouble getting the expression to work. The goal is to sort by the highest difference based on the UNSPSC.  Any help would be appreciated.  Thanks

[Chanty4u]

Try this 

Sum({<Year={"$(=Max(Year))"}>} Amount)

-

Sum({<Year={"$(=Max(Year)-1)"}>} Amount)