To use pivot tables in Microsoft Excel, follow the steps given below:

  • Save the excel sheet with a different name and then try running the pivot table.
  • Remove hidden data, use the following Microsoft article to remove hidden data.

Click the link below to review the online article on Microsoft website:
http://office.microsoft.com/en-us/excel-help/remove-hidden-data-and-personal-information-from-office-documents-HA010037593.aspx