.cab file not downloaded/installed

We are using a 3th party viewer (NetVue) to view documents over the
internet. On a window 2000 everything works fine, but on a Win XP SP2
system (IE 6) the viewer is not installed/downloaded.

If I look in the tempory internet files the .cab file is also not
downloaded.

What is wrong???

The following html is used:

<embed type="image/Print" hidden width="0" height="0">
<applet
name="nv"
code="NetVue.class" archive="/netvue/netvue.jar"
width="100%" height="100%">
<param name="cabbase" value="http://servername/NetVue/netvue.cab">
<param name="server_name" value="servername">
<param name="USERNAME" value="r">
<param name="PASSWORD" value="">
<param name="embed" value="no">
<param name="LOCAL_PRINT" value="yes">
<param name="http_connection" value="both">
<param name="REMOTE_PRINT" value="no">
<param name="ANNOTATIONS" value="no">
<param name="LOCAL_SAVE" value="no">
<param name="STATUS_VISIBLE" value="no">
<param name="TOOLBAR_VISIBLE" value="yes">
<param name="MINIPAGE_VISIBLE" value="no">
<param name="MENU_VISIBLE" value="yes">
<param name="TITLE_VISIBLE" value="Yes">
<param name="HELP_URL" value="nvhelp/nvhelp00.html">
<param name="Image1" value="Netvue:A-436-CG-01R-001.tif">
</applet>