VB เช็คข้อมูลแล้วให้ เปลี่ยนค่าที่เช็คแล้ว query ไม่รัน ครั้งที่สอง

 Dim cn As New OleDbConnection
    Dim c1As New OleDbCommand
    Dim da As New OleDbDataAdapter
    Dim ds As New DataSet

    Dim ma As String

    Dim conn As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\Vb2008\Vbb\Vbb\Hotel.accdb;Persist Security Info=False"

Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
        Dim ab, a1 As String
        cn.ConnectionString = conn
        c2.Connection = cn
        ab = ComboBox7.Text

        Dim ydate As String = Format((DateTimePicker1.Value.Date()).AddDays(ma).AddYears(-543), "M/d/yyyy")
        Dim xdate As String = Format(DateTimePicker1.Value.Date().AddYears(-543), "M/d/yyyy")

        c2.CommandText = "SELECT ROom_id,Check_in,Check_out,STATUS FROM STATUS_ROom WHERE ROom_id = " + ab + " and Check_in = #" + xdate + "# and Check_out = #" + ydate + "# and STATUS = 'Busy'"

        da.SelectCommand = c2

        da.Fill(ds, "STATUS_ROom")
        DataGridView1.DataSource = ds.Tables("STATUS_ROom")


        Try
            a1 = ds.Tables("STATUS_ROom").Rows(0)("STATUS").ToString
            If a1 = "Busy" Then
                MsgBox("ห้อง " + ComboBox7.Text + " ไม่ว่าง ในวันที่ " + xdate + " ถึง " + ydate)
            Else

            End If

        Catch ex As Exception

'อันไม่ไม่เกี่ยวคับคือดึงค่ามาลงtextboxเฉยๆ
            TextBox3.Text = ydate
            TextBox1.Text = xdate
            TextBox4.Text = ComboBox1.Text
            TextBox5.Text = ComboBox2.Text
        End Try
    End Sub