VB.net+Access do simple procedures, database read no problem, but the update time is not successful

Use VB.net+Access to do a simple program, database read no problem, but the update time is not successful, please ask what is the reason, the code is as follows:

```vb.net

 Private Sub ButtonOK_Click(sender As Object, e As EventArgs) Handles ButtonOK.Click
        Try
ObjConn = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|\Resources\DatabaseZuoye.mdb") '链接数据库
            ObjConn.Open()
            Dim SQLstring As String = "update ZuoyeData set IFFocusOn='是' ,IFRenyuanOK='" & ComboBoxRenyuan.Text & "', IFhuanjingOK='" & ComboBoxHuanjing.Text & "',IFLingbao='" & ComboBoxLingbao.Text & "', FocusList='" & RichTextBoxGuanzhuxiang.Text & "', Quyuzhichiren='" & TextBoxZhichengren.Text & "', Guanzhudu=" & ComboBoxGuanzhudu.Text & " where ID=" & LabelXuhao.Text
            'Dim SQLstring As String = "delete from ZuoyeData  where ID=" & LabelXuhao.Text
            MsgBox(SQLstring)
            Dim objComm As New OleDb.OleDbCommand(SQLstring, ObjConn)
            objDa.SelectCommand = New OleDbCommand(SQLstring, ObjConn)
            objDa.SelectCommand.ExecuteNonQuery()
            MsgBox(objDa.SelectCommand.ExecuteNonQuery())                '这里反馈结果还为1，真是奇怪，应该成功了确没有成功
            ObjConn.Close()
        Catch ex As Exception
            MsgBox(ex.Message.ToString)

```