Return previous Month Balances from Running Data

[Anonymous]

I am trying to receive the last month's value for each row here. They all belong to the same item. However, I am only getting some previous monthly values in return, and I am not quite sure why. Here is the variable and DAX command used. Any answer to why only some are returning a value?

[Anonymous]

^ All these values belong to the same NoteNum, but are indexed seperately. 

[Anonymous · Accepted solution]

Nvm. Overcomplicated it. Using PREVIOUSMONTH worked fine, rather than DATEADD