I reviewed your code and it looks correct. As you can see on our online demo - http://demos.telerik.com/silverlight/#Chart/MultipleYAxes
, the series show as expected on our side. That is why, I suppose there is something specific to your setup that leads to the described result. For example, in case you have code that sets the color for each bar, you might use the same code for both series. However, I cannot be sure what exactly is causing the problem, unless I am able to reproduce it locally. That is why, please open a formal support ticket and send me a running test project, demonstrating the problem. I will review the code and do my best to help you fix it.
All the best,
the Telerik team
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