Private Sub cmbEinheit_Change()
'...
    Dim t As Se2TextBox
 
    For Each t In Me.txteingabe
        Select Case LCase(t.Tag)
            Case "sollwert"
                If IsNumeric(txteingabe(t.index).Text) Then
                    txteingabe(t.index).Text = convertValues(CDbl(txteingabe( _
                      t.index).Text), _
                    LCase(Einheit), cmbEinheit.Text)
                End If
        End Select
    Next t
'...
End Sub