Calcule dans une textbox

Private Sub TextBox1_Change()
If Len(TextBox1) = 2 Then TextBox1 = TextBox1 & ":"
End Sub

Private Sub TextBox1_Enter()
Call Calcul
End Sub

Private Sub TextBox2_Enter()
Call Calcul
End Sub

Private Sub Calcul()
Dim bool As Boolean
Dim heure&
Dim minute&
If TextBox1 = "" Or TextBox2 = "" Then bool = True
If Not IsDate(TextBox1) Then bool = True
If Not IsNumeric(TextBox2) Then bool = True
If bool Then
  TextBox3 = ""
  Exit Sub
End If
heure& = CLng(Mid(TextBox1, 1, InStr(1, TextBox1, ":") - 1))
minute& = CLng(Mid(TextBox1, InStr(1, TextBox1, ":") + 1))
TextBox3 = ((heure& * 60) + minute&) * CDbl(TextBox2)
End Sub

Private Sub UserForm_Initialize()
TextBox3.TabStop = False
End Sub

Like "##:##"