Formula using column of cross tab

Hi All ,

I have an issue in calculating a field depending on Day name in every day.  As shown in the picture  the columns are the date  and last number field is the field i have issue with .

I want to calculate in every day  if it was Friday so calculate this   "total_number" * 0,25   Else " total_number " *0.5

I calculated this  formula  but it does not work As it only see  1 day not the two days  :

if ({MISSED_DAYS.FN}="FRIDAY")

then ((GridValueAt(CurrentRowIndex, CurrentColumnIndex, 1))*0.25)

else ((GridValueAt(CurrentRowIndex, CurrentColumnIndex, 1))*0.5)

Note : Missed_days.FN is the name of the day  .     Missed_days.FD is the date  i used "FD" for cross tab  column

Hope i was clear enough .. Thanks