Problem authenticating to a REST service with NTLM though a load balancer

I am using centrasite/mediator 9.7 and I am trying to call a REST service (of sharpoint). the SharePoint 2IIS is behind a load balancer.
wher I try to connect with NTLM transparent Mediator is not returning the header variables returned by 2IIS :
Cookie and Cookie2
This variables are used in the negotiation
as Mediator is not retruning them I am getting 401 Unauthorized at the end

I think this is because my loadbalacer is not able to identify the same serveur that tha negotiation started with because I am not sending the variables

anybody have more info abour this

thank you