Start summing fields after milestone (Date)

[redko_f]

Hey guys I'm quite new to Power BI so I have a question. 
I have two tables Calendar and Unit Tracker. 
In the unit tracker I have fields: 
1) DaysIn (Result of calculation of difference betwen IN and OUT) 

2) IN
3) OUT
4) UnitNum
5) WorkshopEnd
6) LastRefurbish (Last date of workshop for Unit)
In the Calendar the main field which I use is Date filtered by latest OUT date and The first IN date.
What I need to do is summrize DaysIN for the Unit from the moment of the LastRefursbish. 
I was tried to use next formula but I receve and error message: 

Can somebody tell what is wrong and how I need to change formula.

[RaduH]

Hi, as usually in Power BI, there are more ways to achieve the same result>

Prerequisite: please make sure that all dates are formatted as dates: Home->Edit Queries -> Edit Queries - -> Select the columns, right click, Transform -> Data Type: Date.

Alternative 1:

1. Create a Table where you sum days in for each LastRefurbish date.

2. Create a measure which calculates the DaysIn - Last Refurbish:

Simple measure: DATESBETWEEN(<dates>,<start_date>,<end_date>)

More complex / including conditions:

 =CALCULATE(SUM(InternetSales_USD[SalesAmount_USD]), DATESBETWEEN(DateTime[DateKey], 
    DATE(2007,6,1), 
    DATE(2007,8,31) 
  ))

3. Create a relationship between Calendar dates and Last Refurbish and summarize based on Calendar dates.

The posted picture is not visible, I hope this helps. If you tweak a bit around the above solutions you will easily get there - I am sure!