launching program from CHM doesn't work

Hi,

I have a compiled HtmlHelp file (.chm) that launches an external program. It
works well on Windows XP, but not on Vista.
I'm wondering if someone could point out what the problem is.

The code is like this:
<OBJECT id=hhctrl type="application/x-oleobject"
classid="clsid:adb880a6-d8ff-11cf-9377-00aa003b7a11" width=100 height=100>
<PARAM name="Command" value="ShortCut">
<PARAM name="Item1" value=",rundll32.exe,shell32.dll,Control_RunDLL
MAIN.CPL">
</OBJECT>

I tried disabling UAC, but that didn't help at all.

Thanks!