Selection of Graphs

Hello, I have putted three graphs (Bar, Line and Pie) on one report on single Report Header. The both three shown when the report is opened.
But
I want to select particular graph upon selection from Combo in Form. e.g.
if I select All, it must show all charts.
and if I select Bar so it must show only bar chart and if i select pie so it must show only pie chart and so on..

any helps regarding this?

raza