Problem in setting Drill Down path

Problem in setting Drill Down path

I was trying to set "Drill Down Path" bar chart based on the Date Column. When created a new report it inherited the Drill down path set in the column column of table. I unselected the Drill down check box in the report settings.

But when reselected the check box, i can set Year->Quarter->Month. but not showing Week and day. Is this a known problem ?