object reference not set to an instance of an object.

 Private Sub GridView1_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles GridView1.RowDataBound
        Dim DDlCom As DropDownList
        DDlCom = e.Row.FindControl("DdlCom")
        Dim Myda1 As New SqlDataAdapter("Select Code From Tl_ComponentCode order by code", Conn)
        Dim ds1 As New DataSet
        ds1.Clear()
        Myda1.Fill(ds1, "datacom")
        If ds1.Tables("datacom").Rows.Count > 0 Then
            With DDlCom
               [font=Verdana] .DataSource = ds1.Tables("datacom")[/font]
                .DataTextField = "Code"
                .DataValueField = "Code"
                .DataBind()
            End With

        End If

        Dim DdlDmg As DropDownList
        DdlDmg = e.Row.FindControl("DdlDmg")

        Dim Myda2 As New SqlDataAdapter("Select Code_Da From Tl_DamageCode order by Code_Da", Conn)
        Dim ds2 As New DataSet
        Myda2.Fill(ds2, "dataDMG")
        If ds2.Tables("dataDMG").Rows.Count > 0 Then
            With DdlDmg
                .DataSource = ds2.Tables("dataDMG")
                .DataTextField = "Code_Da"
                .DataValueField = "Code_Da"
                .DataBind()
            End With
        End If

        Dim DdlRepair As DropDownList
        DdlRepair = e.Row.FindControl("DdlRepair")
        Dim Myda3 As New SqlDataAdapter("Select Code_Repair From Tl_RepairCode order by Code_Repair", Conn)
        Dim ds3 As New DataSet
        Myda3.Fill(ds3, "dataRep")
        If ds3.Tables("dataRep").Rows.Count > 0 Then
            With DdlRepair
                .DataSource = ds3.Tables("dataRep")
                .DataTextField = "Code_Repair"
                .DataValueField = "Code_Repair"
                .DataBind()
            End With
        End If
    End Sub