This is a known problem with pivot charts. There's information in the
following MSKB article, which suggests recording a macro as you apply
the formatting:

Changing a PivotChart removes series formatting in Excel
http://support.microsoft.com/?id=215904


Stilla wrote:
> Hello: I'm stumped!
>
> I have some charts whose source data comes from pivot tables. I have
> customized the formatting. Everytime I refresh the pivot data, I lose the
> chart formatting and it reverts to the default.
>
> Is there anyway of preventing this while keeping the pivot tables "live?"
>
> thanks


--
Debra Dalgleish
Excel FAQ, Tips & Book List
http://www.contextures.com/tiptech.html