Power pivot - DIVIDE error

[bongielondy]

I have a table, Table 1 that has month, volume and number of working days columns.

Table1
cMonth	Volume	nDays
01.2021	12​	31​
02.2021	3​	28​
01.2021	7​	31​
02.2021	8​	28​
02.2021	14​	28​

nDays is a calculated (added column). Formula used to create nDays is =SWITCH('Table1'[cMonth],01.2021",31,"02.2021",28,"03.2021",31). If a user selects 01.2021 in the pivot chart, the total volume will be 12+7=19. The rate should be 19/31. Total volume for the month should be divided by the working days. For February, 02.2021, total volume will be 3, 8 and 14= 25. Rate = 25/28.

The rate formula is giving me an error. rate:=DIVIDE(SUM('Table1'[Volume]),'Table1'[nDays])
How should I calculate the rate

 

[arunsjain]

Try following

Divide( sum([Volume]), Sum([nDays])/Count([cMOnth]))