The colors in the suggested selectors are the same as the background color for the time slots. This way on hover, you will not see any change.
Do you use the Outlook skin? If you have changed the skin, please change the selectors' name accordingly. In our local tests we were able to obtain the desired result, so I am not sure why this is not working for you. If you continue to experience problems, please send us a small demo project.
the Telerik team