Must declare the scalar variable

Question

Pessoal sabem dizer onde está o erro?

Protected Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button2.Click

        If txtMaquina.Text <> String.Empty And txtMaquinaIP.Text <> String.Empty And txtColaborador.Text <> String.Empty And txtMAC.Text <> String.Empty Then
            Try
                oConn.Open()

                myInsert = "INSERT INTO maquina" & _
                "(nome_maquina) VALUES" & _
                "(@nome_maquina)"

                oCmd.Parameters.Add(New SqlParameter("@nome_maquina", txtMaquina.Text))

                oCmd = New SqlCommand(myInsert, oConn)
                oCmd.ExecuteNonQuery()
                oConn.Close()

                'Response.Redirect("Exibir.aspx")
            Catch ex As Exception
                lblMsg.Text = ex.Message
            End Try

        End If

    End Sub

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