Custom snmp trap not able to generate

Hello , I have script which echo certain message . that i am logging into /var/log/ltm file using 

logger -p local0.err "message"

And 

i have add the custom snmp trap config to /etc/config/user_alert.conf like below :

alert AZ_SAS_TOKEN_EXPIRIED "message " {
snmptrap OID=".1.3.6.1.4.1.3375.2.4.0.413"
}

can anyone suggest where i am going wrong .