I can't seem to re-create the below in BRL (entry-point + accumulate)

I want to combine an entry-point and an accumulate function such as (the below is DRL, which works)

rule "GSS-Sev1-Monitor"
        no-loop true
        dialect "mvel"
        when
            $ticketStatistics : TicketStatistics( $ID : ID == null )
            accumulate($supportTicket:SupportTicket( ticketStatisticsID == $ID , severity == "Sev-1" ) over window:time (5m) from entry-point "gss-support-stream", $num : count( $supportTicket ))
        then
            $ticketStatistics.currentTicketCount = $num;
            update( $ticketStatistics );
        end

I can't seem to re-create this in Guvnor (BRL)