c# - How to update listbox with ObservableCollection data in Win RT -

i trying update listbox form observablecollection don't know doing wrong exception below. new winrt.

the application called interface marshalled different thread. (exception hresult: 0x8001010e (rpc_e_wrong_thread))

<listbox x:name="userlist" horizontalcontentalignment="stretch" margin="12,41,12,12">         <listbox.itemtemplate>             <datatemplate>                 <grid margin="10">                     <grid.columndefinitions>                         <columndefinition width="20" />                         <columndefinition width="150" />                         <columndefinition width="*" />                     </grid.columndefinitions>                     <textblock text="{binding title}" margin="3" grid.column="0" />                     <textblock text="{binding description}" margin="3" grid.column="1" />                     <textblock text="{binding title}" margin="3" grid.column="2" />                 </grid>             </datatemplate>         </listbox.itemtemplate>       </listbox>   

c# code.

protected  override void onviewmodelcollectionchanged(object sender,system.collections.specialized.notifycollectionchangedeventargs e)     {           this.dispatcher.runasync(windows.ui.core.coredispatcherpriority.normal, () =>        {            userlist.itemssource = items;         }).astask().wait();       } 

to update list, implement interfaceдля inotifypropertychanged

class userdata:  inotifypropertychanged     {       public event propertychangedeventhandler propertychanged;       private string _title;      public string title        {                     {                 return _title;             }         set             {              if (_title != value)                 {                   _title = value;                   if (propertychanged != null)                     {                         propertychanged(this, new propertychangedeventargs("title"));                     }                 }             }         }     }