Hello, I am trying to calculate the opportunity win rate per customer by month. My formula is working for some summary fields but not working for others. The formula I am using for "Win Rate" is: WON:SUM / RowCount
I created a test formula and that is "Win Rate Test":WON:SUM/CLOSED:SUM

It is calculating incorrectly on the first customer but correctly on the second in this example: 


This report is showing closed won and closed lost summaries by month with a total column. 

Any help would be greatly appreciated. 

I am updating a lookup field through process builder to look up an accounting period based on a date the user selects. The accounting period format is YYYY-MM. I tried TEXT(YEAR([OpportunityLineItem].LicenseStartDate__c ))+"-" +CASE(TEXT(MONTH([OpportunityLineItem].LicenseStartDate__c )),1, "01",
2, "02",
3, "03",
4, "04",
5, "05",
6, "06",
7, "07",
8, "08",
9, "09",
10, "10",
11, "11",
12, "12",
"None") 

but I am getting an error of expecting text and returning number. Any help?