How to combine two reports in one crystal report in VB.NET

cr.Subreports = cr2

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
      Try
          If con.State = ConnectionState.Open Then
              con.Close()
          End If
          con.Open()

          Dim sql As String

          Dim prn As String = ComboBox2.Text


          Sql = "SELECT dbo.Trainees.Name, dbo.Trainees.GroupName, dbo.Trainees.IDPic, dbo.Trainees.AName, dbo.FollowUp.prno, " +
                " dbo.FollowUp.cycleno, dbo.FollowUp.mo, dbo.FollowUp.dy, dbo.FollowUp.yr, dbo.FollowUp.code, " +
                " dbo.FollowUp.warnings, dbo.FollowUp.wcategory, dbo.FollowUp.wreason, dbo.FollowUp.A, dbo.FollowUp.B, " +
                " dbo.FollowUp.P, dbo.FollowUp.C, dbo.FollowUp.Q, dbo.FollowUp.L, dbo.FollowUp.V, dbo.FollowUp.S, dbo.FollowUp.totalhrs " +
                " From dbo.Trainees INNER Join dbo.FollowUp ON dbo.Trainees.PRNo = dbo.FollowUp.prno " +
                " Where(dbo.FollowUp.prno = '" + prn + "') "


          Dim da As New System.Data.SqlClient.SqlDataAdapter(Sql, con)

          Dim ds As New DataSet8

          da.Fill(ds, "View_8")

          Dim cr As New CrystalReport10()

          cr.SetDataSource(ds)


          Dim sql2 As String

          sql2 = "SELECT dbo.Grades.PRNo, dbo.Trainees.Name, dbo.Grades.CycleNo, dbo.Grades.Results, dbo.Grades.Remarks " +
                 " FROM dbo.Trainees INNER JOIN dbo.Grades ON dbo.Trainees.PRNo = dbo.Grades.PRNo " +
                 " WHERE(dbo.Grades.PRNo = '" + prn + "') "


          Dim da2 As New System.Data.SqlClient.SqlDataAdapter(sql2, con)

          Dim ds2 As New DataSet16

          da2.Fill(ds2, "View_16")

          Dim cr2 As New CrystalReport55()

          cr2.SetDataSource(ds2)
          CrystalReportViewer1.ReportSource = cr
          cr.Subreports = cr2

      Catch ex As Exception
          MsgBox(ex.Message)
          con.Close()
      End Try
      con.Close()
  End Sub