Selection Set Error

I'm using the following code in my acad.dvb!thisdrawing module. The purpose
is to check the drawing for attribute definitions, change them to a new
layer, and prompt you that there are definitions. I am getting reports from
users that they are receiving run-time errors when they exit a drawing and I
don't know why. Anyone have a clue?

Tim Riley

********code****************************************************************
*****

Option Explicit
Public Sub AcadStartUp()

Dim SelSet As AcadSelectionSet
Dim AT As AcadAttribute
Dim FilterType(0 To 0) As Integer
Dim FilterData(0 To 0) As Variant
Dim File As String
Dim FixLay As AcadLayer
Dim SingleLay As AcadLayer
Dim TotLay As AcadLayers

FilterType(0) = 0
FilterData(0) = "ATTDEF"

On Error Resume Next
ThisDrawing.SelectionSets.Add "SelSet"
Set SelSet = ThisDrawing.SelectionSets("SelSet")
SelSet.Clear
On Error GoTo 0

SelSet.Select acSelectionSetAll, , , FilterType, FilterData

If SelSet.Count <> 0 Then
MsgBox "You Have " & SelSet.Count & " Attribute Definition(s) in " &
ThisDrawing.Name & ". Please Change Them To Text."
'Create a new layer
Set FixLay = ThisDrawing.Layers.Add("Fix_Attributes")
FixLay.Color = acRed
Else:
Exit Sub
End If

For Each AT In SelSet
AT.Color = acByLayer
AT.Layer = "Fix_Attributes"
Next

End Sub

Private Sub AcadDocument_Activate()
Call AcadStartUp
End Sub