crystal报告加载失败

我的水晶报告在执行时崩溃了，我可以通过网站查看我的报告，但几分钟后我的报告崩溃了，asp.net告诉我加载报告失败。实际发生了什么问题？y它会在执行期间崩溃吗？

protected void Page_Load(object sender, EventArgs e)
{
    //load report
    ReportDocument RD = new ReportDocument();
    //base on App_Code xsdfile name
    top5movie ds = new top5movie();
    DataTable dt= new DataTable();
    dt.TableName = "Report";
    dt = getAllOrders().Tables[0];
    ds.Tables[0].Merge(dt);
    RD.Load(Server.MapPath("~/CrystalReport2.rpt"));
    RD.SetDataSource(ds);

    CrystalReportViewer1.ReportSource = RD;

    //end load report
}
//report function
public DataSet getAllOrders()
{
    SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
    SqlCommand cmdSelect = new SqlCommand("selectTop5Movie",conn);
    DataSet ds = null;
    SqlDataAdapter dts;
    try
    {
        conn.Open();
        cmdSelect.Connection = conn;
        ds = new DataSet();
        dts = new SqlDataAdapter(cmdSelect);
        dts.Fill(ds, "movieTitle");
        dts.Fill(ds, "userName");
         dts.Fill(ds, "uploadDate");
         dts.Fill(ds, "movieClicks");
    }
    catch (Exception ex)
    {
        throw new Exception(ex.Message);
    }
    finally
    {
        cmdSelect.Dispose();
        if (conn.State != ConnectionState.Closed)
            conn.Close();
    }
    return ds;
}