Limited Categories in a Pie Chart?

[yalinfang]

I have a pie chart with 25 categores.
Does anyone know where I can set the number of categorized pie chart to be displayed cause I can only see maximum of 16 charts.

e.g.

o  o  o  o
o  o  o  o
o  o  o  o
o  o  o  o
            >> There is an arrow here, but not directing to any where cause it's an image.