Ember controller transitiontoRote() in Ember.observer not work

Ember CLI
1

http://localhost:4200/#/account/enable?code=144dc55011bf719381b6597b8860f2f6eb8e611a17cec583b41f8a6b6ebe0f95

but in Ember.observer function transitionToRoute() is not work

account.enable Controller:

import Ember from 'ember';

export default Ember.Controller.extend({

  queryParams: ['code'],
  code: null,

  fromUrl:Ember.computed('code','model',function(){
    let code = this.get('code');
    return code;
  }),
  codeChange: Ember.observer('code', function() {
        let self=this;
        if(code.length>0){
          self.transitionToRoute('account.signin');
    }
  })

});