Display blanks in pivots table (excel 2010)

Hi,

I can find lots of tips how not to show blanks in a pivot table but I do actually want to show them, however they are currently showing as '0' which is misleading to my audience; also I have cells will '*' which I also want to show in the pivot but again these show as '0' - the format of the cells in the raw data in 'number' however I have tried changing this to 'general' or 'text' but to no avail when refreshing the pivot table.

Any help is much appreciated.

Dave