Protect PDF document with Javascript

Pre-created a protection policy with the name "MySecurityPol", and run this code from the console in Acrobat Pro DC, but there is a syntax error! What am I doing wrong?

var DoApplyMySecurity = app.trustedFunction( function(){
    var oMyPolicy = null;    app.beginPriv();
    // First, Get the ID of My Security Policy
    var aPols = security.getSecurityPolicies()
    for(var index=0;index<aPols.length;index++){
        if(aPols[index].name == "MySecurityPol"){            oMyPolicy = aPols[index]; break;
        }
    }
    if(oMyPolicy == null){ app.alert("Policy Not Found"); return; }
    // Now, Apply the security Policy
    var rtn = this.encryptUsingPolicy({oPolicy: oMyPolicy });
    if(rtn.errorCode != 0) app.alert("Security Error: " + rtn.errorText); app.endPriv();
});
I want to put a code in the form field to protect the document, when I click on the form, the code is launched and the document is encrypted.