Code that's causing me trouble

PHP Code:

Ext
.define('IDB.selectbox.SelectBox', {
    
extend 'Ext.form.ComboBox',
    
alias 'widget.IDB.selectbox.SelectBox',
    
//clearFilterOnReset:false,
    
triggerAction'all',
    
lastQuery''
    
linkToCombo undefined,
    
linkFilter : function() {
        if(
this.linkToCombo) {
            var 
linkedCombo this.ownerCt.getComponent(this.linkToCombo.comboID);
            
console.log(this.linkToCombo);
            
console.log(this.linkToCombo.filterField+linkedCombo.getValue());
            
this.getStore().filter([{
                
property this.linkToCombo.filterField,
                
value linkedCombo.getValue(),
                
exactMatch true
            
}]);
        }
    },
    
initComponent : function() {
        
this.callParent(arguments);
        if(
this.linkToCombo) {
            var 
linkedCombo Ext.ComponentQuery.query('#'+this.linkToCombo.comboID);
            
this.addManagedListener(linkedCombo'select', function() { //This is the problem line
                
this.clearValue();
                
this.fireEvent('select');
            }, 
this);
            
this.on('expand'this.linkFilterthis);
        }
    }
}); 
Error:
item.on is not a function, ext-debug-all.js (line 5613):

PHP Code:
// Within the Ext.util.Observable section:
5604 else {
5605    managedListeners.push({
5606       itemitem,
5607       enameename,
5608       fnfn,
5609       scopescope,
5610       optionsoptions
5611    
});
5612
5613    item
.on(enamefnscopeoptions);// Here's where the app breaks.
5614