DAX Date tables in power pivot and power bi

[dicken]

Hi,
Can someone tell me if Powe pivot and Power Bi work differently in relation to date / Calendar Tables,
So if I have a meaure ;

 SUM(TslaesTable[Sales} )

and I use this in a pivot table which is just has Dates in the Rows, if i use the dates from the sales table I get what I would expect the sales
for that date, but if I use the dates from the Calendar table ( yes they are related) I just get the grand total of sales.
I've done exactly the same in power bi, and both calendar and sales dates get the right answer.
I'm never sure about calendar tables, yes I know I need one for time intel functions, is there a definitive guide to their use someone can point me to.

Richard.

 

[dicken]

To update my own question, I have since replicated what I had and now the totals work fine with the dates from the Calendar table,
so now the question becomes what might I have been doing to make it that none of the measure worked with the date table?