Having difficulties with using group by columns

[AidenNoh]

Hello, I'm having difficulties with group by function.

I was trying to calculate specific column by using group by with sum of specific column, but it didn't work.

Instead, a message is constatntly appears that specific column contains duplicate value that cannot be applied.

I Don't know why this message is constantly appears and why my calculation is not working.

[jgeddes]

Assuming you are using the Group By feature in Power Query, I have run into issues in the past with trailing spaces existing in cells that are not easily seen. Power Query doesn't group them together but when loading into Power BI you get the error that a single value has duplicate. Long story short I use the TRIM feature on my grouping column prior to grouping in Power Query to get rid of unwanted whitespaces.

Hope this helps.