Slicer problems

I have constructed a large pivot table and attempted to put some slicers on. Sheets will not

1. let me choose the specific column I wish to slice on,
2. when I have a slicer like "Name" the slicer only shows me eight names of the several hundred in the sheet, and
3. the slicer for grade...1 - 7 does not see grade five.

I'm an Excel guy and not proficient with sheets, any help would be appreciated.