FirstSortedValue giving Nested Aggregation Error

[s4ni9r]

Item	URL	Style	Sales
10012	Image1	NY30	1000
10013	Image2	NY30	550
10014	Image3	NY30	4000
10015	Image4	NY30	3000
10016	Image5	NY30	10000
10017	Image6	NY30	450
10018	Image7	NY30	360
10019	Image8	NY30	4000
20019	Image1	NY50	4000
20019	Image2	NY50	95000
20019	Image3	NY50	1323
20019	Image4	NY50	11200
20019	Image5	NY50	7689

I need the image corresponding to the maximum sales for each style, i have written an expression

FirstSortedvalue(URL,-Aggr(sum(sales),Style,Item)) -- this is giving nested aggregation error as i am using this in another expression.

Can we get the same logic in script  like this FirstSortedvalue(URL,-Aggr(sum(sales),Style,Item)).

Can anyone please help..