Pareto 80/20 calculation for items making up 80% of Sales

[kcantor]

I have tried this several different ways and always end up crashing my program. I am in need of guidance.

I have a Sales Performance Table that lists my total sales for the company. this is related to the Item Table by the Code field. I would like to create a visual that shows which items (by code) that make up 80% of the total sales. As all of my calculation attemps have resulted in a crash, I am not sure which to include here as I am 7 attemps in and all of those measures and fields are still in the data set.

Any advice?

I used this as a foundation : http://dutchdatadude.com/power-bi-pro-tip-pareto-analysis-with-dax/

The measures I adapted are:

Total Amount= SUM(SalesPerformance[LineSales])

Amount All Products=CALCULATE([Total Amount], ALLNOBLANKROW('Item'[Code]), SalesPerformance[LineType]="Item")

Item Rank=RANKX(ALLNOBLANKROW('Item'[Code]), [Total Amount])

Pareto%Item=DIVIDE([ParetoValueItem], [Amount All Products], BLANK())

Pareto Value Item=SUMX(TOPN([Item Rank], ALLNOBLANKROW('Item'[Code]), [Total Amount]), [Total Amount])

Any Advice: @Sean or @greggyb ?