SAMEPERIODLASTYEAR in a Calculated Column

In your measure, you are trying to get the Sum for the date one year ago.  If that is what you are looking for (vs. getting a sum over a broader previous period like quarter), this expression would do it too:

Sales LY =
VAR ayearago =
DATE ( YEAR ( Append1[Date]) - 1, MONTH ( Append1[Date] ), DAY ( Append1[Date] ) )
RETURN
CALCULATE (
SUM ( Append1[Value] ),
ALL ( Append1 ),
Append1[Date] = ayearago,
VALUES ( Append1[Peer] )  
)

I am not sure what columns you need to keep constant (Peer, Source, etc.) so you can add/replace a Values() term like this for each one to keep the same for the calculation.

If this works for you, please mark it as solution.  Kudos are appreciated too.  Please let me know if not.

Regards,

Pat

See if my Time Intelligence the Hard Way provides a different way of accomplishing what you are going for.

https://community.powerbi.com/t5/Quick-Measures-Gallery/Time-Intelligence-quot-The-Hard-Way-quot-TITHW/m-p/434008

Anonymous , Make sure you use Date calendar for that

YTD QTY = TOTALYTD(Sum('order'[Qty]),'Date'[Date])
LYTD QTY = TOTALYTD(Sum('order'[Qty]),dateadd('Date'[Date],-1,year))
Previous Year = CALCULATE(SUM('order'[Qty]), PREVIOUSYEAR('Date'[Date]))
// Forced from Today
YTD QTY forced= 
var _max = today()
return
calculate(Sum('order'[Qty]),DATESYTD('Date'[Date]),'Date'[Date]<=_max)
//calculate(TOTALYTD(Sum('order'[Qty]),'Date'[Date]),filter('Date','Date'[Date]<=_max))
//
LYTD QTY forced= 
var _max = date(year(today())-1,month(today()),day(today()))
return
CALCULATE(Sum('order'[Qty]),DATESYTD(dateadd('Date'[Date],-1,year)),'Date'[Date]<=_max)
//TOTALYTD(Sum('order'[Qty]),dateadd('Date'[Date],-1,year),'Date'[Date]<=_max)
//Forced from Max date this year
YTD QTY forced= 
var _max = maxx('order',[Order date])
return
calculate(Sum('order'[Qty]),DATESYTD('Date'[Date]),'Date'[Date]<=_max)
//calculate(TOTALYTD(Sum('order'[Qty]),'Date'[Date]),filter('Date','Date'[Date]<=_max))

LYTD QTY forced= 
var _max1 =maxx('order',[Order date])
var _max = date(year(_max1)-1,month(_max1),day(_max1))
return
CALCULATE(Sum('order'[Qty]),DATESYTD(dateadd('Date'[Date],-1,year)),'Date'[Date]<=_max)
//TOTALYTD(Sum('order'[Qty]),dateadd('Date'[Date],-1,year),'Date'[Date]<=_max)


//

This Year = CALCULATE(sum('order'[Qty]),filter(ALL('Date'),'Date'[Year]=max('Date'[Year])))
Last Year = CALCULATE(sum('order'[Qty]),filter(ALL('Date'),'Date'[Year]=max('Date'[Year])-1))

To get the best of the time intelligence function. Make sure you have a date calendar and it has been marked as the date in model view. Also, join it with the date column of your fact/s. Refer :
https://radacad.com/creating-calendar-table-in-power-bi-using-dax-functions
https://www.archerpoint.com/blog/Posts/creating-date-table-power-bi
https://www.sqlbi.com/articles/creating-a-simple-date-table-in-dax/

See if my webinar on Time Intelligence can help: https://community.powerbi.com/t5/Webinars-and-Video-Gallery/PowerBI-Time-Intelligence-Calendar-WTD-YTD-LYTD-Week-Over-Week/m-p/1051626#M184


Appreciate your Kudos.

You could also try the below :