java - Cannot load/save properties of the ViewModel's property -

i have problem accessing property of object inside viewmodel. got unreached destination error. pointers please? thanks.

error message:

target unreachable, 'toto' returned null

basically, error when fill in textbox , click somewhere in window. when use other viewmodel's property (which string), works expected.

setup:

i use jboss studio. app running on jboss 7. follow guide http://books.zkoss.org/wiki/zk_installation_guide/quick_start/create_and_run_your_first_zk_application_with_eclipse_and_maven create project.

zul file:

<window apply="org.zkoss.bind.bindcomposer"         viewmodel="@id('vm') @init('com.maylab.fault.ticketsviewmodel')"         title="trouble ticket" width="600px" border="normal">     <hbox style="margin-top:20px">         <textbox value="@save(vm.toto.name)"></textbox>         <label value="@load(vm.toto.name)"></label>     </hbox>  </window> 

viewmodel:

package com.maylab.fault;  import org.zkoss.bind.annotation.*;  import com.maylab.fault.person;  public class ticketsviewmodel {      private string ticket;     private string test;     private person toto;      public person gettoto() {         return toto;     }      public void settoto(person toto) {         this.toto = toto;     }      public string gettest() {         return test;     }      public void settest(string test) {         this.test = test;     }      public string getticket() {         return ticket;     }      public void setticket(string ticket) {         this.ticket = ticket;     }   } 

person class:

package com.maylab.fault;  public class person {          private string name;          public person(){          }          public person(string name){             this.name = name;         }          public string getname() {             return name;         }          public void setname(string name) {             this.name = name;         }   } 

if check viewmodel, have wrote code private person toto; , get/set method know toto=null resolve issue have change code

private person toto = new person(); 

this resolve issue.