In some cubes, not every dimension cuts every measure group. That is, some measures, when put in the pivot table, are not affected when sliced by any member from a given dimension. Without detailed knowledge of the cube, you might not know which dimensions cut which measure groups.
If you disable the SmartFilter, then the PTE displays all of the dimensions and measures available, with no filtering applied.
With SmartFilter enabled, the PTE automatically shows only those measure groups and dimensions that cut the members that have been placed in the pivot table. The set of dimensions that is displayed is the intersection of the set of dimensions cut by the measures in the pivot table. Likewise, the set of measure groups that is displayed is the intersection of the set of measure groups cut by the dimensions in the pivot table).
