Margins are page settings which are applied on each physical page. Placing items in the space occupied by margins is not possible. Thus please post the code of the report in order to check its settings.
On a side note, if the issue is in the way the report is paged test setting the sections KeepTogether property based on the Understanding Pagination
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.