Hi CJ chavez,
If you want to create a new theme, you will have to package it in a separate assembly, as outlined here.
However, if you only want to style several elements, you can do so with XAML Styles, there's no need to create a whole custom theme and try to apply it with the telerik StyleManager.
We provide the source code of our themes in our RadControls for Silverlight package. You can find them in the Themes folder in your RadControls for Silverlight installation folder. They are a good place to start building custom themes.
Also, when setting themes in Silverlight, make sure you reference the relevant theme's assembly.
Please don't hesitate to contact us with any further inquiries.
the Telerik team
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