Unique Values From Selected Range

I use the following code to extract a unique list of values and paste the list to a specified range:



Public Sub extract_unique()
Dim a As Range, v As Range, w(), i As Long, r As Range
Set a = Selection
Redim w(1 To a.Count, 1 To 1)
With CreateObject("scripting.dictionary")
.comparemode = vbTextCompare
For Each v In a
If Not IsEmpty(v) And Not .exists(v.Value) Then
i = i + 1: w(i, 1) = v.PrefixCharacter & v.Value
.Add v.Value, Nothing ..............
The code gets interrupted at this line:


If Not r Is Nothing Then

with the following error: "Code execution has been interrupted."

When I click debug, the line above is highlighted. If I click the sideways triangle to resume code execution it finishes normally. What can I do to stop my code from being interrupted?