Excel Workbook thread problem

Dim file As String = "C:\Techform.xlsx"


     Dim xlApp_2 As New Excel.Application
     xlApp_2.Visible = False
     xlApp_2.DisplayAlerts = False
     Dim oBook As Excel.Workbook
     oBook = xlApp_2.Workbooks.Open(file)

     Dim oSheet As Excel.Worksheet


     oSheet = oBook.Worksheets(1)
     objConnection.Open()
     adapter_view.SelectCommand = New SqlCommand()
     adapter_view.SelectCommand.Connection = objConnection
     adapter_view.SelectCommand.CommandText = "SELECT * FROM TECHNICAL_AMS_CALC_GARGANTUA "
     adapter_view.SelectCommand.CommandType = CommandType.Text
     adapter_view.Fill(dataset, "GARGANTUA_AVERAGE_Data")
     dataTable_CALC = dataset.Tables("GARGANTUA_AVERAGE_Data")
     adapter_view.Dispose()
     For h As Integer = 0 To dataTable_CALC.Rows.Count - 1
         ' lets modify a1 and a2

         SoG_AVG = dataTable_CALC.Rows(h).Item("VPM_SPEED_THROUGH_WATER_AVG")
         oSheet.Range("E3").Value = dataTable_CALC.Rows(h).Item("VPM_SPEED_THROUGH_WATER_AVG")
         oSheet.Range("F3").Value = dataTable_CALC.Rows(h).Item("VPM_SPEED_THROUGH_WATER_MAX")

         ' save

         oBook.SaveAs(file + " " + dataTable_CALC.Rows(h).Item("ACTION_DATE") + ".xlsx", CreateBackup:=False)
         oBook.Close()
         xlApp_2.Quit()
     Next