C# / VB.NET - [vb.net]eseguire più file audio

ciao a tutti, sto iniziando a costruire un programmino dove far suonare alla pressione del pulsante play un file wave, il programma e composto da 3 pulsanti: play, stop, open ( apro il file con openfiledialog) 1 combobox: visualizzo il percorso del file, una label.text: visualizzo il nome del file, ora fin qui ci sono riuscito e funziona alla grande, ma se voglio duplicare la stessa applicazione sullo stesso form e quindi: 3 pulsanti di cui: play, stop, open etc... e vado a cambiare i rispettivi percorsi quindi il secondo pulsante di play con il secondo opefiledialog2 etc..e voglio far suonare ad ogni pulsante play un suono diverso, questi mi da errore e mi esce la seguente scritta:

System.ArgumentNullException was unhandled
Message="L'argomento non può essere Nothing. Nome parametro: location"
ParamName="location"

l'idea e di voler creare tanti pulsanti play da far corrispondere ad ogni pressione del medesimo pulsante un suono diverso. vi posto il codice da me scritto:

spero di essere stato chiaro di essere aiutato
allego file immagine del form.

Public Class Form1


Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
My.Computer.Audio.Play(ComboBox1.Text)
End Sub

Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged

End Sub

Private Sub OpenFileDialog1_FileOk(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles OpenFileDialog1.FileOk
ComboBox1.Text = OpenFileDialog1.FileName
End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
My.Computer.Audio.Stop()
End Sub

Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
OpenFileDialog1.ShowDialog()
Label1.Text = OpenFileDialog1.SafeFileName
End Sub

Private Sub Label1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label1.Click


End Sub

Private Sub Button6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click
My.Computer.Audio.Play(ComboBox2.Text)
End Sub

Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
OpenFileDialog2.ShowDialog()
Label2.Text = OpenFileDialog2.SafeFileName
End Sub

Private Sub ComboBox2_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox2.SelectedIndexChanged

End Sub

Private Sub Button9_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button9.Click
My.Computer.Audio.Play(ComboBox3.Text)
End Sub

Private Sub Button7_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button7.Click
OpenFileDialog3.ShowDialog()
Label3.Text = OpenFileDialog3.SafeFileName
End Sub

Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
My.Computer.Audio.Stop()
End Sub

Private Sub Button8_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button8.Click
My.Computer.Audio.Stop()
End Sub

Private Sub Button11_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button11.Click
My.Computer.Audio.Stop()
End Sub

Private Sub Button14_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button14.Click
My.Computer.Audio.Stop()
End Sub

Private Sub Button12_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button12.Click
My.Computer.Audio.Play(ComboBox4.Text)
End Sub

Private Sub Button10_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button10.Click
OpenFileDialog4.ShowDialog()
Label4.Text = OpenFileDialog4.SafeFileName
End Sub

Private Sub Button15_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button15.Click
My.Computer.Audio.Play(ComboBox5.Text)
End Sub

Private Sub Button13_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button13.Click
OpenFileDialog5.ShowDialog()
Label5.Text = OpenFileDialog5.SafeFileName
End Sub
End Class

L'eccezione non c'entra col fatto che tenti di riprodurre più suoni, ma viene lanciata semplicemente perché il parametro di Play è vuoto (ComboBox.Text).