need to know why this groovy is not working on activity

Summary

need to know why this groovy is not working on activity

Content

the below groovy is giving me the below warning please need your assistance as the requirement is :

"cm need to sent notification for each assigned user on each activity in the action plan and I used the below trigger but isn't work so please advise"

Warning(7,13) : Cannot find matching method oracle.jbo.script.groovy.BaseScriptGroovy#sendNotification(groovy.lang.Binding, java.lang.String). Please check if the declared type is right and if the method exists.

 

 

 

 if (isAttributeChanged('OwnerName')) {
    try {
        def recipientPartyId = OwnerName
        def messageText = 'An Action notification (default message).'