Error message while calculating days between 2 dates

[Ashley1]

I am trying to calculate days 2 dates but it is giving me error message; A single value for column 'Date' in table 'TableName' cannot be determined. This can happen when a measure formula refers to a column that contains many values without specifying an aggregation such as min, max, count, or sum to get a single result.

I created a new measure with: 

DATEDIFF('TableName'[Date], TODAY(), DAY)

I tried same calculation for new column as well but it didn't work either.

[DataNinja777 · Accepted solution]

Hi @Ashley1 

I am assuming that you are trying to write a measure and not a calculated column.  In a dax measure there is a golden rule which states that "you cannot reference a naked column", which means that you have to wrap it up in an aggregation function.  This is because, using your current formula, dax measure cannot determine out of the column, 'TableName'[Date], which row you want your calculation to be based on.  

Please try the following formula instead, for example.  

Best regards,