Access - Actualizar cuadro combinado dependiente

Private Sub CmbNombre_AfterUpdate()

    Me.CmbApellido.RowSource = "SELECT Apellido FROM Tabla WHERE Nombre = '" & Me.CmbNombre & "' GROUP BY Apellido"

    Me.CmbApellido = Null

    Me.CmbEdad = Null

    Me.txtColor = Null

    Me.txtColor.BackColor = 16777215

End Sub

Private Sub CmbApellido_AfterUpdate()

    Me.CmbEdad.RowSource = "SELECT Edad,Color FROM Tabla WHERE Nombre = '" & Me.CmbNombre & "' AND Apellido = '" & Me.CmbApellido & "'"

    Me.CmbEdad = Null

    Me.txtColor = Null

    Me.txtColor.BackColor = 16777215

End Sub

Private Sub CmbEdad_AfterUpdate()

    Me.txtColor = Me.CmbEdad.Column(1)

    Call colores

End Sub

Private Sub colores()

    Select Case Me.CmbEdad.Column(1)

        Case "Verde"

            Me.txtColor.BackColor = 65280

        Case "Azul"

            Me.txtColor.BackColor = 16737843

        Case "Morado"

            Me.txtColor.BackColor = 14614640

        Case "Amarillo"

            Me.txtColor.BackColor = 65535

        Case "Rojo"

            Me.txtColor.BackColor = 255

        Case "Negro"

            Me.txtColor.BackColor = 0

    End Select

End Sub