VBA Developers Handbook, 2nd Edition. questions on procedures and functions

so im reading VBA Developer's Handbook, 2nd edition and i have a question about a function (why it's returning 0, when it should be greater than 0). see below:

Public Function dhCountInCaseS(strText As String, strFind As String, Optional lngCompare As VbCompareMethod = vbBinaryCompare) As Long
    Dim lngCount As Long
    Dim lngPos As Long
    'this search is case sensitive so "A" is not the same as "a"
    'if there's nothing to find, there surely can't be an found so return 0
    If Len(strFind) > 0 Then
        lngPos = 1
        Do
            lngPos = InStr(lngPos, strText, strFind, lngCompare)
            If lngPos > 0 Then
                lngCount = lngCount + 1
                lngPos = lngPos + Len(strFind)
            End If
        Loop While lngPos > 0
    Else
        lngCount = 0
    End If
    dhCountIn = lngCount
End Function

and here is the procedure

Sub Count_Vowels()
    Dim strText As String
    Dim intVowels As Long
    
    strText = "THIS IS A TEST OF THE NATIONAL BROADCASTING SYSTEM"
    
    intVowels = dhCountInCaseS(strText, "A") + dhCountInCaseS(strText, "E") + dhCountInCaseS(strText, "I") + _
    dhCountInCaseS(strText, "O") + dhCountInCaseS(strText, "U")
    
    Debug.Print intVowels
End Sub

Is there a problem with the function or how i'm implementing the procedure?