Create automatically a change request from RITM

Hello,

I want to create a change request automaticaaly from RITM when this one is created, and in order to do that I created a business rule as the following but it is not working : 

Script : 

(function executeRule(current) {

    var chg = new GlideRecord('change_request'); 
    chg.initialize();

    chg.type = current.variables.model.toString();  
	chg.category = current.variables.category.toString();
    chg.short_description = current.variables.short_description.toString();
    chg.priority = current.variables.priority.toString();
    // Ensure service reference is valid
    if (current.variables.service) {
        chg.cmdb_ci = current.variables.service;
    }

    chg.state = 1; // Optional: Defaults to "New"
    var chgSysId = chg.insert();

    if (chgSysId) {
        gs.info('Change Request ' + chgSysId + ' created from RITM ' + current.sys_id);
    } else {
        gs.error('Failed to create Change Request from RITM ' + current.sys_id);
    }

})(current);

and the mapping must be with the variables in RITM : Model - Category - Short description - Priority - service.