Excel pivot table filter

I'm trying to apply a filter to some data so that only values of less than 100 show. However, after I enter the filter with the drop-down box (Column filters>value filters>less than 100) and say OK, all of the data in the table disappears. It's driving me crazy, any Excel whizzes here???

What does it give if you do greater than 100?

The normal mistake is to have text instead of values in pivot tables so they don't filter by values.