Excel 2010 Pivot Table add Calculated Field based on certain text in a Report Filter

Can someone please tell me if there is a way to create a calculated field in an Excel 2010 pivot table that will find all the Transaction Types (Report Filter) with “transportation” in them and make the field Quantity 0 and leave all other quantities the same? I do not want the quantity of transportation added in twice and may not have the flexibility of adding a column to the raw data.

I used the formula below in a calculated field and it does not match the values using the added column to the data file.

=IF(ISERROR(SEARCH("*transportation*",'Transaction Type')),Quantity, 0)

I am trying to get the sum of Quantity field to equal the AdjQuantity field using a calculated Pivot field and not add a new column to the data.