extjs - Error ext-all-dev.js:12300 Error: Cannot read property 'length' of undefined -

i have application in extjs works when creating view sends me following error:

error: can not read property 'length' of undefined ext-all-dev.js: 12300

procude error in line of code ext-all-dev.js (i used pause on uncaught exception in chrome):

getrendertree: function() {          var me = this,               result = me.callparent(arguments)               i, len;            (i = 0, len = result.length; <len; + +) {              result [i] = me.transformitemrendertree (result [i]);           }           return result;       }  

i created 3 classes:

1 - name ext.ux.panelfooter , extending 'ext.panel.panel'

2 - name ext.ux.panelheader , extending 'ext.panel.panel'

3 - name ext.ux.toolbar , extends ext.toolbar.toolbar

help please, thank you.

edit / update:

this code

var panelcenter = new ext.panel.panel({         region: 'center',         id: 'centerpanel',         title: 'system admin',         enabletabscroll: true,         border: true,         layout: 'fit',               bodypadding: '0 0 20 20',         layout:'column',         items: [{             columnwidth: 1,             layout:'column',             frame: false,             border: false,             items: [{                 columnwidth: .25,                 html: ' ',                 frame: false,                 border: false             },{                 title: 'welcome',                 columnwidth: .5,                 height: 200,                 style: 'padding: 10px;',                 align: 'right',                 items: [{                         xtype: 'panel',                         layout: 'column',                         frame: false,                         border: false,                         style: 'padding: 3px;',                         items: [{                             columnwidth: 1,                             layout: 'form',                             frame: false,                             border: false,                         }]                     }]             }]         }]     }); 

i see - comma missing in declaration:

var me = this, result = me.callparent(arguments) i, len;

so, result gets undefined.