funzioni di controllo con IF e visual basic

Private Sub CommandButton1_Click()
Dim a As Integer
Dim b As Integer
a = TextBox1.Text
b = TextBox2.Text
If verifica(a, b) Then
Call prodotto(a, b)
Else
Call somma(a, b)
End If
End Sub

Public Function verifica(a As Integer, b As Integer)
If (a > 10 And b > 100) Then
verifica = True
Else
If (a < 10 And b < 100) Then
verifica = True
Else
If (a < 10 And b > 100) Or (a > 10 And b < 100) Then
verifica = False
End If
End If
End If
End Function

Public Sub prodotto(a As Integer, b As Integer)
Label1.Caption = a * b
End Sub

Public Sub somma(a As Integer, b As Integer)
Label1.Caption = a + b
End Sub

Private Sub UserForm_Click()

End Sub