BIRT_retrieving Data (from Data sets) in scripted Chart

Hello everyone,
I'm using BIRT All-in-one Version working on a report where i created a chart using script. I added a chart through Chart-builder( any charts type), and then went to the script button and in the beforeGeneration() i coded the chart and changed it's type to Bar chart

When you open my attached report, you'll see on the Layout a scatter chart, but when you view the report it displays a bar chart which i programmed in the script window.

Here i'm using s scripted data source.

but If you look into the script, you'll see that I've added custom Data per Hand like (A,B,C.....) and numbers like (244,250.....)

Now the question is : How can I a retrieve the data from my Data set ,that i created into the Chart-script. ????

Please see the following picture for better Understanding. Also the example is attached with this post.