Listvariable leeren!?!?!?

Private Sub CommandButton1_Click()
Dim Antwort
Dim Antwort2
If Quelle = "" Then
MsgBox ("Please enter the source directory!")
Else
Antwort = MsgBox(Quelle, 4, "Directory take over?")
If Antwort = vbYes Then
Dim Datei As String
Datei = Dir(Quelle & "\*.HIN")
Antwort = MsgBox(Datei, 4, "Is the designation of the files correctly called?") 'Ist die Bezeichnung der Dateien korrekt?
If Antwort = vbYes Then
Do While Datei <> ""
If Len(Datei) > 28 Then
MsgBox ("The file name " & Datei & " is too long! Filename correct?")
Exit Do
Else
If Len(Datei) < 28 Then
MsgBox ("The file name " & Datei & " is too short! Filename correct?")
Exit Do
Else
ReDim Preserve Liste(Z)
Liste(Z) = Datei
Z = Z + 1
Datei = Dir
If Z = 0 Then
MsgBox ("No files in the indicated directory!")
End If
End If
End If
Loop
If Z > 0 Then
Me.ComboBox1.List = Liste()
MsgBox (Z & " files were found!")
End If
End If
End If
End If
End Sub