It looks to me that the text is having the same color as it's background. In our demo, if you use Black skin it looks correct:
So I believe it is from some custom styles that you have set in your project. Review your CSS and/or use the browsers developer tools to inspect the element and see what styles are applied and change them if needed.
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to the blog feed