Hi Snow Lu.
I just wanted to let you know that I found a solution to my PivotTable problem.
There is a setting under Data in Excel's options that was turned on and caused the error. The option is "Prefer the Excel Data Model when creating PivotTables, QueryTables, and Data Connections." This option must be unchecked when a user is working with Excel files saved in the older *.xls (97-2003) file format. Otherwise, they will see the error in question. I never got the error when working with the newer file formats, which I thought strange. So, that led me to think this was an issue affecting newer features in Excel.
Here's a screenshot: