snort sfportscan log file output does not have event_id, instead is event_ref and the value is 0

Question

my config is follow:

preprocessor sfportscan: proto { all } \
scan_type  { all } \
sense_level { high } \
logfile { alert }

when I run snort,and use nmap to scan,then log file output as follow:

Time: 02/23-12:54:21.183932 
event_ref: 0
[Source ip address] -> [Destination ip address] (portscan) TCP Portscan
Priority Count: 9
Connection Count: 10
IP Count: 1
Scanner IP Range: [Destination ip address]:[Destination ip address]
Port/Proto Count: 10
Port/Proto Range: 981:12174

but the snort doc say as this:

Time: 09/08-15:07:31.603880
event_id: 2
192.168.169.3 -> 192.168.169.5 (portscan) TCP Filtered Portscan
Priority Count: 0
Connection Count: 200
IP Count: 2
Scanner IP Range: 192.168.169.3:192.168.169.4
Port/Proto Count: 200
Port/Proto Range: 20:47557

If there are open ports on the target, one or more additional tagged packet(s) will be appended:

Time: 09/08-15:07:31.603881
event_ref: 2
192.168.169.3 -> 192.168.169.5 (portscan) Open Port
Open Port: 38458

I do not has event_id,instead is event_ref and its value is 0