Highlight Cell based on Today -15 days

Hello. I really need some help. I am new to PowerBi, I did browse for a solution but this is a bit beyond me. All I want is to highlight in red the cells that are older than 15 days (or if it blank). Each column is data from a different source. I read refences about Conditional Formatting but I couldnt get them work. I also saw stuff about Measures (Today() or Now()), custom columns, DAX and it is a bit over my head for now.

When I create a measure and try to apply it to a Conditional Format rule it just goes blank, as if there was an error with the measure or it can't be used against a date column, i really dont know. 

Any help is greatly appreciated. Thanks.