ช่วยผมด้วยมีปัญหา .ExecuteNonQuery()... ExecuteNonQuery requires an open and available Connection. The connection's current state is closed

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        cm = New OleDbCommand("insert into machine values( '" & TextBox1.Text & "','" & TextBox2.Text & "','" & TextBox3.Text &             "','" & TextBox4.Text & "','" & TextBox5.Text & "','" & ComboBox1.Text & "')", cn)
        cm.ExecuteNonQuery()
        displaydata()
        cleardata()
        autocode()
End Sub

Imports System.Data
Imports System.Data.SqlClient
Public Class Form2

    Private Sub Label2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label2.Click

    End Sub



    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        Label2.Text = Today
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim sQL As String
        sQL = "insert into Add(Date,Number,Namebook,Peice)"
        sQL = sQL & "VALUES('"
        sQL = sQL & TextBox1.Text & "','"
        sQL = sQL & TextBox2.Text & "','"
        sQL = sQL & TextBox3.Text & "')"
        Dim cmd As SqlCommand
        cmd = New SqlCommand
        With cmd
            .CommandType = CommandType.Text
            .CommandText = sQL
            .Connection = conn()
            .ExecuteNonQuery()   (มันขึ้น eroor ตรงนี้คับช่วยทีนะคับ)
        End With
        MsgBox("เพิ่มข้อมูลเรียบร้อยแล้ว")
        TextBox1.Clear()
        TextBox2.Clear()
        TextBox2.Clear()
    End Sub

End Class

Private Sub ButtonSave_Click(ByVal sender As Object, ByVal e As EventArgs) Handles ButtonSave.Click

        If Not (IsNumeric(TextNumFloors.Text) OrElse Is Integer(TextNumFloors.Text)) Then

            MessageBox.Show("จำนวนชั้นต้องเป็นเลขจำนวนเต็ม")
            Exit Sub

        ElseIf Not (IsNumeric(TextRoomsPerFloor.Text) OrElse IsInteger(TextRoomsPerFloor.Text)) Then

            MessageBox.Show("จำนวนห้องในแต่ละชั้นต้องเป็นเลขจำนวนเต็ม")
            Exit Sub

        ElseIf Not IsNumeric(TextNumFloors.Text) Then

            MessageBox.Show("ค่าเช่าต้องเป็นตัวเลข")
            Exit Sub
        End If

        If hasRows Then
            sql = "UPDATA Ref SET " & "NumFloors = @floors, " & "RoomsPerFloor = @rooms, " & "Rental = @rent"

        Else
            sql = "INSERT INTO Ref(NumFloors,RoomsPerFloors,Rental) " & "VALUES(@floors, @rooms, @rent)"
        End If

        command = New SqlCommand(sql, connection)
        command.Parameters.Clear()
        command.Parameters.AddWithValue("floors", TextNumFloors.Text)
        command.Parameters.AddWithValue("rooms", TextRoomsPerFloor.Text)
        command.Parameters.AddWithValue("rent", TextRental.Text)

        Dim r As Integer = command.ExecuteNonQuery()

        If r = 1 Then
            MessageBox.Show("ปรับปรุงข้อมูล")
            connection.Close()
            FormRef_load(sender, e)
        Else
            MessageBox.Show("เกิดข้อผิดพลาด")
        End If
    End Sub