acrobat will not close after manipulating bookmark

The access 2007 vba code below works fine, but it leaves acrobat open after it closes. I don't see that I have done anything odd or out of order, but I must be missing something. Any ideas would be greatly appreciated.

Thanks,
Dan

Below is the code that can be pasted into a command button on a form in access.

Const SampleFilePath = "C:\Debug.pdf"

' Create a PDDoc IAC object.
' Since we don't need to launch Acrobat Viewer on the screen, we don't have
' to create Acrobat App object.

Dim pdDoc As Object 'CAcroPDDoc
Set pdDoc = CreateObject("AcroExch.PDDoc")
If pdDoc Is Nothing Then
MsgBox "Failed to create Acrobat PDDoc object."
End
End If

' Open the source PDF document
Dim rc As Long
rc = pdDoc.Open(SampleFilePath)
If rc <> -1 Then
MsgBox "Failed to open PDF document " & SampleFilePath
End
End If

' Acquire the Acrobat JavaScript Object interface from the PDDoc object
Dim jsObj As Object
Set jsObj = pdDoc.GetJSObject

'**************************************************************************************
'I will try to add my logic here
Dim objBkm As Object
Dim a As Variant
Dim s As String
Dim Counter As Integer
Set objBkm = jsObj.bookmarkroot
a = objBkm.Children

For Counter = 0 To UBound(a)
s = s & "Counter: " & Counter & " Name: " & a(Counter).Name & " Open: " & a(Counter).Open & " Style: " & a(Counter).Style & vbCrLf
Next Counter
MsgBox s

'************************************************************************************
'finish

pdDoc.Close

Set a = Nothing
Set objBkm = Nothing
Set fields = Nothing
Set formApp = Nothing
Set avDoc = Nothing
Set jsObj = Nothing
Set pdDoc = Nothing