Last price calculation of the month

[Syndicate_Admin]

Friends I need to calculate the last sale price of the month of all products.
I have 3 tables, related to each other, Facts = Sales, Dim = Inv, Dim = calendar.

First I do the sum of the field I need with a classic sum.
Sum$Hist = SUM('powerbi factventas'[priceundd])
Then I use another measure
UltimoPM = CALCULATE([Sum$Hist],LASTNONBLANK(Calendar[Date],[Sum$Hist]))
In theory it works for me, the detail is that the first sum adds all the sales prices per product and what I need is to add them only once by articles. If anyone can help me. Thank you in advance

[lbendlin]

Please provide sanitized sample data that fully covers your issue.
https://community.powerbi.com/t5/Community-Blog/How-to-provide-sample-data-in-the-Power-BI-Forum/ba-...
Please show the expected outcome based on the sample data you provided.

https://community.powerbi.com/t5/Desktop/How-to-Get-Your-Question-Answered-Quickly/m-p/1447523