Collect Payload after 100-Continue

I am trying to have the load balancer respond as the server. The POST's that are coming in do not require any data returned, but are using the Expect: 100-Continue header. The below works and I see the transaction complete via a tcpdump, but why does the logging of the payload not work? Trying to figure out where the events stack up once taking over as the server.

[CODE]

when HTTP_REQUEST {

if { [HTTP::host] eq "mycompany.com" }{

HTTP::collect [HTTP::header "Content-Length"]

if { [HTTP::header Expect] eq "100-continue" }{

HTTP::respond 100 noserver

}

}

}

when HTTP_REQUEST_DATA {

log local0. "[HTTP::payload]"

}

[/CODE]