DAX help - Last year YTD is wrong

Anonymous , Try with help from date table , marked as date table

YTD Sales = CALCULATE(SUM(Sales[Sales Amount]),DATESYTD('Date'[Date],"12/31"))
Last YTD Sales = CALCULATE(SUM(Sales[Sales Amount]),DATESYTD(dateadd('Date'[Date],-1,Year),"12/31"))

YTD QTY forced=
var _max = today()
return
if(max('Date'[Date])<=_max, calculate(Sum('order'[Qty]),DATESYTD('Date'[Date])), blank())
//or
//calculate(Sum('order'[Qty]),DATESYTD('Date'[Date]),filter('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
if(max('Date'[Date])<=_max, CALCULATE(Sum('order'[Qty]),DATESYTD(dateadd('Date'[Date],-1,year)),'Date'[Date]<=_max), blank())
//OR
//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)

Power BI — Year on Year with or Without Time Intelligence
https://medium.com/@amitchandak.1978/power-bi-ytd-questions-time-intelligence-1-5-e3174b39f38a
https://www.youtube.com/watch?v=km41KfM_0uA