Lookup Across Worksheets

I am attempting to perform a vlook across multiple worksheets -- per the instructions provided here - [url]

My results are coming back with an Invalid Name Error or #NAME?. The formula I am using is: =VLOOKAllSheets(A17,C$20:C$5000,1,FALSE)

The custom excel function is:

Dim wSheet As Worksheet
Dim vFound

On Error Resume Next

For Each wSheet In ActiveWorkbook.Worksheets
With wSheet
Set Tble_Array = .Range(Tble_Array.Address)
vFound = WorksheetFunction.VLookup _
(Look_Value, Tble_Array, _
Col_num, Range_look)
End With
If Not IsEmpty(vFound) Then Exit For
Next wSheet

Set Tble_Array = Nothing
VLOOKAllSheets = vFound