New Measure with Columns in different tables

[apagan]

I've created a New Measure Column using the following formula: 

DaysToComplete = DATEDIFF(LocationVisits[sampleddate],WorkOrders[StartDate],DAY)

But, I am getting an error message, "A single value for column 'sampleddate' in table 'LocationVisits' cannot be determined." I believe the issue may be that the two columns are in different tables - Is it possible to create a New Measure Column in one of the tables based on columns in different tables?

[KHorseman · Accepted solution]

You have to have some way to find a single value for LocationVisits[sampleddate] on each row of WorkOrders. LocationVisits[sampleddate] is a column. How does this formula know which row of that column it's supposed to use?

If there is a many to one relationship between WorkOrders and LocationVisits you may be able to use RELATED(LocationVisits[sampleddate]).