เรื่องการสั่งพิมพ์ print รบกวนพี่แนะนำทีคับ Object reference not set to an instance of an object

 Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim connStr As String = ConfigurationManager.ConnectionStrings("testConnectionString").ConnectionString.ToString()
        Dim conn As New SqlConnection(connStr)
        conn.Open()

        Dim da As New SqlDataAdapter("select * from Table_borrow a  " & _
"   join Table_device b on (b.H_deviceID=a.G_deviceID) " & _
"   join Table_member c on (c.A_memberID=a.G_memberID) " & _
"   where G_borrowID = '" & Request.QueryString("returnID").ToString() & "' ", conn)
        Dim ds As New DataSet
        da.Fill(ds, "Table_borrors")

        Dim report As New CrystalDecisions.CrystalReports.Engine.ReportDocument() ' สร้างออบเจกต์ของ Engine ของ Crystal Reports 
        report.Load(Server.MapPath("rpt.rpt"))
        report.SetDataSource(ds.Tables("Table_borrors"))
        CrystalReportViewer1.ReportSource = report
    End Sub
End Class