Power Query Custom Column with year and month

Hi to all, i try to add a custom column from my two date fields Start and End, but after, i got an error: 

Expression.Error: The value isn't a single-character string.
Details:
Value=202103

For create a custom column list i use this: 

{Date.ToText([Start_Date__c], "yyyyMM")..Date.ToText([End_Date__c], "yyyyMM")}

If i use {Date.Month([Start_Date__c])..Date.Month([End_Date__c])}

it gives me correct month values but, i need yearmonth format like yyyyMM

Can someone help me?

My every row, it's a week with start and end dates, if week only in one month, i expected to see like 202105, if week start from one month and end on another, i expected to see 2 values, 202105, 202106