Hi Tony Isaac,
I am not quite sure what you mean by index number. When I run the provided code for the following RadSlider, I get January, February, March, etc:
As I am not sure which version of the assembly you use, I tested with the latest - 2009.1.402.
In case this does not help you, please prepare and send me a simple running project, demonstrating the problem as well as detailed information on the expected result.
Best wishes,
Tsvetie
the Telerik team