Error on DateDiff function

Hello all,

I created a report using PowerBI Desktop and everything is workfine. When I upload it to PowerBI Report Server (on premises) I got an error on a specific column that uses the following function:

RFCDaysOpen = DATEDIFF(RFC[Created],RFC[Modified],DAY)

All tabs uses the same datasource (CSV File), which is being loaded and updated successfully.

Working on PBI Desktop:

Not working on PBI Report Server

Thanks