Changing a frame in a double frameset setup

[BazzaOz]

Don't know if this can be done.
I have a site with multiple framesets

1st frameset has two frames called 'banner' and 'main'.
2nd frameset which sits inside frame 'main' also has two frames called 'mainindex' and 'mainbody'.

Now, I want it so a page placed inside 'mainbody' will trigger a change in 'banner'.
The below code works fine with one frameset, can it be made to work in the above example.

<script language="javascript" type="text/javascript">
var lem = (self.innerHeight != null && self.innerHeight == 0);
if ((parent.banner==null || parent.banner!='changeframe') && !lem) {
parent.banner.location.replace('bannerhome.asp');
}
</script>

[BazzaOz]

Thanks Dave. How easy was that!
:)