First let me direct you to one of our online demos: Point, Gantt, Bubble Chart
(select "Bubble" from the drop down list). This will give you a notion of how the RadChart in Asp.Net Ajax draws a bubble chart. In short - the YValue is the center of the ellipse and the YValue2 is the ellipse's height.
If you comment out the plot area from the code that you have provided - you will start to see a more meaningful output.
However, I think that this might not be what you want exactly and this is why I have attached a simple app to get you started with one of the ways to create a bubble chart. I have also attached a snapshot of the output that I get when I run this code.
Hope this is of help.
the Telerik team
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