Logstash filter using grok and multiline

Debug output from logstash

{"@source"=>"rendez-vous", "@tags"=>["multiline"], "@fields"=>{"thread_id"=>["2812"], "pid"=>["42122"], "loglevel"=>["DEBUG"]}, "@timestamp"=>"2012-11-19T16:39:22.302Z", "@source_host"=>"devsandbox", "@source_path"=>"/", "@message"=>"TrackingService::SendTag(), eventName = screenpagenavig, eventData = ", "@type"=>"rendezvous"}

issue with multiline

filter {
	multiline {
		type => "rendezvous"
		pattern => "^#"
		negate => true
		what => "previous"
	}
	grok {
		type => "rendezvous"
		pattern => "#%{USERNAME:thread_id}\|%{NUMBER:pid}\|\[%{USERNAME:sandbox}\]\[%{LOGLEVEL:loglevel}\]\[%{TIMESTAMP_ISO8601:timestamp}\]%{GREEDYDATA:msg}"
	}
	date {
		type => "rendezvous"
		timestamp => "ISO8601"
	}
	
	mutate {
        type => "rendezvous"
        replace => [ "@source_host", "%{sandbox}" ]
        replace => [ "@message", "%{msg}" ]
        replace => [ "@source", "rendez-vous"]
	}
	mutate {
	    type => "rendezvous"
	    remove => [ "sandbox", "timestamp", "msg" ]
	}
}

Original message in plain text

TrackingService::SendTag(), eventName = screenpagenavig, eventData = 
{
	"curscreen" : "Home",
	"duration" : 16140,
	"player" : 42122,
	"prevscreen" : "Login"
}

Full original message received (watch for double newlines):
#3228|42122|[devsandbox][DEBUG][2012-11-19T16:52:22.015Z]TrackingService::SendTag(), eventName = screenpagenavig, eventData =

{

"curscreen" : "Home",

"duration" : 18234,

"player" : 42122,

"prevscreen" : "Login"

}