Cannot get all rows from Rad Grid-View with DataPager

RadGrid1.AllowPagging = false;
RadGrid1.Rebind();

        foreach (GridDataItem item in RadGrid1.MasterTableView.Items)
        {

        }

RadGrid1.AllowPagging = true;
RadGrid1.Rebind();

(or)

RadGrid1.MasterTableView.AllowPagging = false;

        foreach (GridDataItem item in RadGrid1.MasterTableView.Items)
        {

        }

RadGrid1.MasterTableView.AllowPagging = true;