StreamWriter text file gets created but contains no lines - vb.net

Question

I'm trying to write some text lines to a little log file in a Windows Form application and I cannot see why no lines are written. The file gets created OK and all of the following executes without error but when I open the new file with Notepad, there are no lines. Key snippets follow:
Dim sFileName = App_Path() & "\logs\" & sJobName & ".log"
Try
Using fs As FileStream = New FileStream(sFileName, FileMode.Append, FileAccess.Write)
Using w As StreamWriter = New StreamWriter(fs)
Dim s As String = "Beginning execution (JobName=" & sJobName & ")"
Log(s, w)
s = "Connection in effect: " & BuildConnectString()
Log(s, w)
Dim loader As New Importer
loader.LoadData(Me.txtFN.Text, w)
End Using
End Using
Catch ex As Exception
MsgBox(ex.Message)
End Try
Public Sub Log(logMessage As String, w As StreamWriter)
w.WriteLine("{0} {1}: {2}", DateTime.Now.ToLongTimeString(), _
DateTime.Now.ToShortDateString(), logMessage)
End Sub
and then I'm trying to write to this log from a different class which has been passed the StreamWriter as a parameter:
Public Function LoadData(ByRef filename As String, _
ByRef w As StreamWriter) As String
Dim s As String = "Test logging from loader class"
Mainform.Log(s, w)
In this little test, I am expecting to see 3 lines but I'm getting nothing. I cannot see what I am doing wrong.

Answer 1

It works for me, but if the code doesn't work for you, you can use code like this ...
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim sFileName = App_Path() & "\logs\" & sJobName & ".log"
Try
Dim s As String = "Beginning execution (JobName=" & sJobName & ")"
Log(s, sFileName)
s = "Connection in effect: " & BuildConnectString()
Log(s, sFileName)
Dim loader As New Importer
loader.LoadData(Me.txtFN.Text, sFileName)
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
Public Sub Log(logMessage As String, StrPath As String)
IO.File.AppendAllText(StrPath, String.Format("{0} {1}: {2}", DateTime.Now.ToLongTimeString(), DateTime.Now.ToShortDateString(), logMessage) + vbCrLf)
End Sub
Public Function LoadData(ByRef filename As String, _
StrPath As String) As String
Dim s As String = "Test logging from loader class"
Log(s, StrPath)
End Function