Can;t set reference to pivot cache object

[Glory]

Dim a As PivotCache
 
Set a = ThisWorkbook.PivotCaches.Add _
        (SourceType:=xlDatabase, _
        SourceData:=Sheets("Sheet1").Range("A:J"))
 
'MsgBox a.Index
 
ThisWorkbook.Sheets("Table6").PivotTables(1).CacheIndex = a.Index

The index of "a" is "0", even though I can .Count five other caches in my workbook. I receive "Application or object-defined error" when the CacheIndex of the existing table is let to match the index of "a".

 

[Glory]

This thread explains how I'm currently getting around this problem, but I wouldn't mind having an actual solution.