datasource of Gridview of from a dynamic search becomes null

I have a page for creating a report . In that page i uses a user control for dynamically searching and showing gridview. the gridview is bonded from the usercontrol part and is being shown in the report page. The Gridview contains a checkbox which i use to select the multiple gridview rows for creating report. When i click on the button for generating report which is in report page, I uses

  Gridview gdView = (GridView)DySrch.FindControl("gridview");

where DySrch is the page containing grid view when i check on gdView it shows datasource as null How can i solve this issue? How can retain the gridview values along with checkbox checked from report page?