I tested your code and everything works as expected (here is a screencast capture
which illustrates this and attached is the test project). Please note that the Bubble Chart widget was added in Kendo UI Q2 2012
and will not work with previous versions of the product. Please give a try with version 2012.2.710 or latter.
the Telerik team
Join us on our journey to create the world's most complete HTML 5 UI Framework - download Kendo UI