This technique is wrong because when you will refresh your pivot table the references of the cells will change. First select any cell in the pivot table. Adding percentage to a pivot table its very easy.
Therefore you must use the column name in your formula instead.
Pivot Table calculated fields do not support ranges in formulas. In the Formula box make changes to the formula -- in this example the percentage was changed from 3 to 4. In the Summarize value field by box click the summary. Therefore you must use the column name in your formula instead.