Did you include the modified CSS files to the page where the ToolBar is located? In case you didn't, you should, since this is required for the custom skins to get applied :)
Additionally, you should set the EnableEmbeddedSkins
property of the ToolBar to false
Please read more about applying (registering) custom skins here
the Telerik team
Check out Telerik Trainer
, the state of the art learning tool for Telerik products.