Hiya,
Basically, it means that because of the number of fields that you have specified in your pivot table, with all the sub-totals in place, the pivot table will exceed the maximum number of rows that Excel can handle.
The easiest way to overcome this is add 4 fields to the data area, create your pivot table, click on each field and take the sub-totals out, the go back to wizard and add more fields to the data area.
You need to repeat this step until you have all your fields on your pivot table.
HTH
Tim