MIN and MAX aggregate functions not working in BI Publisher repot for a String type in Pivot.

In my BI Publisher report, I have a pivot table with two measure columns 'Equipment Code' and 'Bad Order Code'.
Both are VARCHAR.I used Oracle BI Analysis as my source Data Model.When I try to use these two columns as measures, I noticed the MIN and MAX are greyed out in the Pivot table.I also noticed in BI Publisher report, the MIN and MAX are only applicable to numeric types and not for strings,unlike OBIEE.Cannot a String type have Count, First, Last, Maximum, and Minimum   functions applicable in BI Publisher report.

But the same works if I choose a Data Table instead of Pivot.B/c in a Data Table I can use 'No Formula' option and display the value as is.