Variable Scope And Printing

I am trying to create a primitive counter. My idea is to write a value to a file, read it, add one and write it back. The file as a single value tab-delimted of 5000. The code below produces the odd output on debug. I really cant understand it.


Public Function nextInv() As Integer
Dim fname As String
Dim fnum As Integer
Dim stringArray()
Dim invNum As Integer

fnum = FreeFile()
fname = "nextInv.txt"

stringArray() = parse(OpenRecordClassesFn(fname), vbTab)
For i = UBound(stringArray) + 1 To LBound(stringArray)
invNum = stringArray(i)
Next
If FileExists(fname) Then
Open fname For Output As #fnum
End If
invNum = invNum + 1
Debug.Print "invNum"
Print #fnum, (invNum & vbTab)
Close #fnum
invNum = invNum + 1

End Function
Public Sub testHarness()
Debug.Print nextInv()
End Sub

with a output of
5000
invNum
0

and the value in the file of 1. It should be 5001.