Your report is too wide to fit on the specified physical page size in the Report.PageSettings
properties. You can see a warning sign in the top left corner of the report designer, when the report is wider than the configured physical page size.
You can find more information on the described behavior in the Horizontal Paging
section of the Understanding Pagination
To fix the issue either reduce the width of your report items, or modify the report's PageSettings
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.