Pivot Table Will Not Filter A Single Character Item

I am coding in excel 2007 vba to create a pivot table based on data on the tab. Although my code is more complicated than the code below, I believe I have narrowed my problem down to the fact that whenever I attempt to filter a single character value I encounter a Run-time error '1004': Unable to get the PivotItems property of the PivotField class.

As an example I ran the following code which worked:

ActiveSheet.PivotTables("Tentatives_Summary_PivotTable").PivotFields("FAMILY").PivotItems("(blank)").Visible = False 
ActiveSheet.PivotTables("Tentatives_Summary_PivotTable").PivotFields("FAMILY").PivotItems("Test").Visible = False

'this works

However, when filtering for "J" I encounter the run-time error '1004':

ActiveSheet.PivotTables("Tentatives_Summary_PivotTable").PivotFields("FAMILY").PivotItems("J").Visible = False

'this does not work