Error in DatesinPeriod formula

[Syndicate_Admin]

Nice day

I'm using the datesinperiod metric to calculate the moving sum of 12 months of warehouse parts outputs but it throws me the error

Calculation error in measure 'Metricas'[Salidas12MM]: A date column containing duplicate dates was specified in the call to function 'DATESINPERIOD'. This is not supported

Salidas12MM = Calculate
(sum(TransactionItems[QTY]),
DATESINPERIOD(TransactionItems[OutDate],
MAX(TransactionItems[OutDate]),-12,MONTH))

[johnt75]

When using the time intelligence functions you need to have a properly formatted date table, which has only 1 entry for each day. Set up a date table, mark it as a date table and set up a relationship from the date table to your transactions table and then use columns from the date table in any visuals, filters and formulas.