HTTP load balancing NW 2004

We recently upgraded our hardware and OS. Hardware is 64 bit and OS is Win 2003 with MSSQL 2005. Since then our HTTP load balancing has not worked. BEX and RFC load balancing okay. We are using EP 6 for SSO to BW. In portal config we are using port 8100 for the message server. Nothing has changed there. We did cluster our backend when we upgraded. I do not know if we left something off (parameters) or something is missing. We are using the message server as load balancing. Does the App servers need something to let the message server know they are out there ?