this is my code but its not woking. any one can help

global class LeadProcessor implements Database.Batchable<sObject> {
    global Database.QueryLocator start(Database.BatchableContext bc){
          String query= 'SELECT Name, LeadSource from Lead';
        return Database.QueryLocator(query);
    }
    global void execute(Database.BatchableContext bc, List<Lead> scope){
        
        for(Lead l: scope){
            l.LeadSource ='Dreamforce';
           
        }
        update scope;
    }
    global void finish(Database.BatchableContext bc){
        
    }
}