updating pivot tables
 

I have a question about pivot tables. Whenever I change data in the
datasource of a particular pivot table and refresh the pivot table, no
changes take place. I am not changing the range, only data within cells.
I have another pivot table where I can change the data and refresh the pivot
table and everything updates as it should.
Does anyone know what the problem is? I am using Excel 2000 on WinXP.