Using a measure in a filter returns 0 while using a fixed number returns my value

[jmkvalsund]

I've created a measurea M_StartDate in the way like
"M_StartDate = CALCULATE(MAX('Table1'[DateID]),FILTER('Table1....." etc
where DateID is an integer-column and I get a value in M_StartDate like 20230920 (showing M_StartDate on a card), which is what I want.

Then I want to use this measure in another measure, like 
"  M_Value = CALCULATE(SUM('Table1'[Col1]), FILTER('Table1','Table1'[DateID]=[M_StartDate]))  "
but this leaves M_Value blank.
However, if I define M_Value like this
"  M_Value = CALCULATE(SUM('Table1'[Col1]), FILTER('Table1','Table1'[DateID]=20230920]))  "   
, then I get the result I want. 

Why?

Regards,
John Martin

[jmkvalsund · Accepted solution]

FYI: I found a way, had to assign the measure to a variable:

M_Value =  
VAR var_M_StartDate = [M_StartDate]
RETURN
CALCULATE(SUM('Table1'[Col1]), FILTER('Table1','Table1'[DateID]=var_M_StartDate))