Weird download problem

[Things]

Hi, I am making a small application to automatically download an image that updates every hour. It works, except the application seems to download duplicates of the same image, even though when I visit the URL myself, it shows the newest image.

I thought something might have been in the cache, and it was just using that instead. I have inserted some cache clearing code, however was just wondering (While I wait for the hour ) if anyone had any other idea's as to why it would do this?

My code (without cache clearing stuff)

Dim Hour As Integer

Private Declare Function URLDownloadToFile Lib "urlmon" Alias _
    "URLDownloadToFileA" (ByVal pCaller As Long, ByVal szURL As String, _
    ByVal szFileName As String, ByVal dwReserved As Long, _
    ByVal lpfnCB As Long) As Long
    
Dim errcode As Long
Dim url As String
Dim localFileName As String



Private Sub StartBtn_Click()
Timer1.Enabled = True
End Sub

Private Sub Stop_Click()
Timer1.Enabled = False
Hour = 0
End Sub

Private Sub Timer1_Timer()
Hour = Hour + 1
Label2.Caption = "Seconds until next image: " & 3600 - Hour
If Hour = 3600 Then
    Hour = 0
    Dim CDT As String
    Dim CDT1 As String
    Dim CDT2 As String
    CDT = Now
    CDT1 = Replace(CDT, "/", "-")
    CDT2 = Replace(CDT1, ":", ".")
    url = "http://www.goes.noaa.gov/sohemi/sohemiloops/ircolgms/8.jpg"
    localFileName = "C:\Loops\" & CDT2 & ".jpg"
    errcode = URLDownloadToFile(0, url, localFileName, 0, 0)
    If errcode = 0 Then
    Label3.Caption = "Download Successful"
    Label1.Caption = "Last download: " & Now
    Else
    Label3.Caption = "Error Downloading"
    Label1.Caption = "Failed download: " & Now
End If
End If
End Sub

Regards,
Dan