Prior Year To Date Frustration

[CJANE]

All:

I have been battling the abiliy to display YTD and Prior YTD.  My dataset is very simple - example is below:

Date	Value
4/5/2021	5
4/4/2021	5
4/3/2021	5
4/2/2021	5

My expressions are

YTD:  

YTD = TOTALYTD(SUM('Sheet1'[Value]), 'Sheet1'[Date])

Prior Year to Date:

LYTD = CALCULATE(Sheet1[YTD],(SAMEPERIODLASTYEAR(Sheet1[Date])))

If I add the date to my visual I am able to get the value I expect for each date.

I cant figure out why the sum of Prior YTD has 605 and not 480.  If I remove the individual date from the visual my numbers are incorrect.

Very Frustrated - any help would be appreciated.

[MattAllington]

There are rules that you must follow to use these functions. The most important is that you need to use a calendar table. I cover this topic extensively here https://exceleratorbi.com.au/power-bi-calendar-tables/

Once you understand the calendar, I have an article here about how time intelligence works. https://exceleratorbi.com.au/power-bi-calendar-tables/