Excel code stopped working

I have some code that takes a validation list and enters it into a combo box which allows the user to use a form of autocomplete and then outputs the results into the desired cell, it used to work, but for a reason i cannot find the code has stopped working.. when i try copy pasting into a new workbook, it fails again!

what have i messed up?

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
Dim str As String
Dim cboTemp As OLEObject
Dim ws As Worksheet
'Dim wsList As Worksheet
Set ws = ActiveSheet
On Error GoTo errhandler
'Set wsList = Sheets("ValidationLists")


If Target.count > 1 Then GoTo exitHandler

Set cboTemp = ws.OLEObjects("TempCombo")
  On Error Resume Next
If cboTemp.Visible = True Then
  With cboTemp
    .Top = 10
    .Left = 10
    .ListFillRange = ""
    .LinkedCell = ""
    .Visible = False
    .Value = ""
  End With
End If

  On Error GoTo errhandler
  If Target.Validation.Type = 3 Then
    'if the cell contains a data validation list
    Application.EnableEvents = False
    'get the data validation formula
    str = Target.Validation.Formula1
    str = Right(str, Len(str) - 1)
        With cboTemp
      'show the combobox with the list
      .Visible = True
      .Left = Target.Left
      .Top = Target.Top
      .Width = Target.Width + 15
      .Height = Target.Height + 5
      .ListFillRange = str
      .LinkedCell = Target.Address
    End With
    cboTemp.Activate
  End If

exitHandler:
  Application.ScreenUpdating = True
  Application.EnableEvents = True
  Exit Sub
errhandler:
  Resume exitHandler

End Sub