Based on the provided information it seems the necessary grid styles are not applied on the page. Please review if all CSS files are loaded correctly. Also here are the options how you can use the custom skins:
1. Include the necessary CSS files for custom skin in your project manually:
- by RadStyleSheetManager
please go to this help topic for more info.
2. Using ASP.NET Themes.
3. Create custom assembly manually or by Skin Assembly Builder.
Building a custom assembly is the best option allowing you to control easily the downloaded CSS files as it is fully compatible with RadStyleSheetManager. This will improve the performance as well.
I hope this helps.
Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.