Format X-Axis using pivot charts issues.

Hi

It seems i can't upload from work. So i'll have try to be very accurate :

I have a data table formatted this way:
- colum 1 = item name
- column 2 = item category
- colum3 ... colum 230 = date (representing sales volume for 1 day)

I can easily plot a graph that will show me the sale volume with all the days in the x-axis

For some oddball reason, my brain doesnt seem to get how to do this using a pivot chart!

Anyone has an idea about what i'm doing wrong ?

Cheers,
N