New Post: offline openstreetmap?

In principle, your code looks similar to what worked for me, so I don't have a definitive solution. FWIW, here is the code that is called from the FormOpen event of my Access 2003 VBA program (it uses a library function to parse the current filename):

Private Sub ConfigureOfflineMaps()
Dim sFilename As String
Dim sPathname As String

With axMap.Tiles
     .DoCaching(tkCacheType.Disk) = True
     .DoCaching(tkCacheType.RAM) = False
     dhParsePath CurrentDb.Name, sPathname, sFilename
     .DiskCacheFilename = sPathname & "\" & APPLICATIONNAME & ".db3"  ' dynamic, to this project
     .MaxCacheSize(tkCacheType.Disk) = 500
End With

End Sub