Issues with running a Procedure in Excel 2003

Hi,

I'm new to VBA and following a book called Mastering Excel 2003 Programming with VBA to learn. I'm stuck on one of the examples given in the book. Please see the details below:

1: I've created an Excel sheet under C:\Examples\ named Example.xls. The sheet1 os the excel has data in Column B3 (="animal"), Column B4 (="art") and Column B5 (="test"). The pupose of the code (Below) is to make the column bold if the data starts with "a".

2: As given in the book, I've added a module to this sheet & copied the below code to the module:

Sub SimpleListProcessing()
    ' Declare our varibles
    Dim wb As Workbook
    Dim rg As Range

    ' Initialize our variables
    Set wb = Workbooks.Open("C:\Examples\Example.xls")
    Set rg = wb.Worksheets("Sheet1").Range("B3")

    ' Loop through cells moving down one cell
    ' until an empty cell is found
    Do Until IsEmpty(rg)
        If Left(rg.Value, 1) = "A" Then rg.Font.Bold = True
        Set rg = rg.Offset(1, 0)
    Loop

    ' Dereference object variables
    Set rg = Nothing
    Set wb = Nothing
End Sub

3: However, when I try to execute the above mentioned code, the strange thing is that Nothing Happens. What I mean is that No Error is thrown & nor does the data in sheet1 is made bold.

Can someone pls help me understand what exactly is the issue here?

Note: Just to make sure if other piece of code is running through a module, I added the below code to module & it works (Gives me an Output):

Sub ExitForExample()
    Dim nLastRow As Integer
    Dim nColumn As Integer
    Dim nRow As Integer
    Dim ws As Worksheet

    Set ws = ThisWorkbook.Worksheets(1)
    nLastRow = 15
    nColumn = 1

    For nRow = 1 To nLastRow
        If ws.Cells(nRow, nColumn).Address = "$A$7" Then
            Debug.Print "Found cell. Exiting for loop."
            Exit For
        Else
            Debug.Print ws.Cells(nRow, nColumn).Address
        End If
    Next

    Set ws = Nothing
End Sub