vb macro with URLDownloadToFile does not work from Mac

Hi
I am trying to download images from an intranet site using VB Macros ( Excel for Mac 2011)
I use URLDownloadToFile and pass the ur

Heres part of the code:
I pass "http://intranet/images/first'jpg" as linkPath
and "Macintosh HD:Users:acdhd:Desktop:" as dest.

Public Function DownloadURLtoFile(linkpath As String, dest As String) As Boolean
done = URLDownloadToFile(0, linkpath, dest, 0, 0)
End Function

This does not return any error, but file does not get downloaded.
Similar one works for windows though.
I can also view the file http://intranet/images/first'jpg in the browser.
Appreciate any help to see why this does not work for mac

Thanks
Anitha