MOM not working.. Please help

Sorry, try this:

Volume LM2 =
VAR varCurrentMonth =
    MAX( 'Fiscal Year Conversion'[YearMonth] )
VAR varPreviousMonth =
    CALCULATE(
        MAX( 'Fiscal Year Conversion'[YearMonth] ),
        'Fiscal Year Conversion'[YearMonth] < varCurrentMonth
    )
VAR Result =
    CALCULATE(
        SUM( 'Opportunity Tracker 2.0'[Annual Volume LBS] ),
        'Fiscal Year Conversion'[YearMonth] = varPreviousMonth
    )
RETURN
    Result

I am doing this without any data or model. If you need further help, please provide data, ideally a PBIX file via a share service (dropbox, onedrive, etc) that has no confidential data.

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