average distinct users per month

[nick9one1]

I have a table that contains information on users accessing a webpage. 

I'm using the following measure to get unique users per day (this is used for the line chart and is correct).

count_of_customer = 
    COUNTROWS (
       SUMMARIZE ( 'cr20b_commscampusauditlogs3', 'cr20b_commscampusauditlogs3'[UserId], 'cr20b_commscampusauditlogs3'[CreationTime].[Date])
    )

I'd also like to include a table that has the monthly average. 

I have tried creating a second measure but using [CreationTime].[Month] instad of Day. This is in the table on the right, showing 622 users.  But the value is clearly wrong, as the max unique users per day is around 340. 

Can anyone suggest what I have done wrong?

[swikritee_p · Accepted solution]

@nick9one1 ,  Create a Date table and join the Date (Without time) with Date of date table and create a measure given below 

Avg of Month =
calculate(
Averagex(Values('Date'[Year Month]) , calculate(
COUNTROWS (
SUMMARIZE ( 'cr20b_commscampusauditlogs3', 'cr20b_commscampusauditlogs3'[UserId], 'Date'[Date])
))), removefilters('date'))