NLB Load balancing with sessions

I have a problem with Windows 2000 NLB and my e-commerce site.
I have 2 servers in an NLB system both run IIS and have HTTP and HTTPS
with the same certificate installed on both.

I use session variables to store various things about each user, 1 of
those things is the basket contents.
Generally the user browses the http://www.xyz.com site and populates the
basket.
The NLB sticky sesions seem to work fine here.

That aside, when the user checks out from the basket page, I send them
to the https://www.xyz.com using a POST form (with no data to transfer
as it's
all stored in session variables). At this point, if there where no NLB,
the session variables would definately remain as sessions are protocol
independent.
However, when using NLB, it appears that this is not the case.

The site seems to 'lose' all session data setup on the
http://www.xyz.com site, hence the basket contents. Of course what is
happening is that the NLB is re-negotiating the host for that client on
that IP. And ends up using a different server for the
https://www.xyz.com Very confusing for the customer.

I don't see why NLB should affect this, on a single server system, this
would work fine, every time (according to what i've read).

Does anyone know if the NLB will direct me to a different machine when I
swap from HTTP (80) to HTTPS (443) ?



ANY help would be great

Andy