extjs 4 : store callback issue - php

Question

I'm working on a Extjs 4 application and I'm at a point where I need to create view components dynamically.
I have a store that's loaded with new items when I select a value from a combobox. And I want to create a new view component for each item the new store has.
I'm using Extjs 4 with the MVC architecture.
This is the function that creates a new combobox that's fired when I choose an Item from another combo :
function createComboBox(label) {
var combo = new Ext.form.ComboBox({
displayField: 'combo',
typeAhead: true,
mode: 'local',
forceSelection: true,
triggerAction: 'all',
emptyText: 'Select item...',
selectOnFocus: true,
fieldLabel: label
});
return combo;
}
This is the code inside my "select combobox" handler event :
onSelectedValue: function (combo) {
var selected = combo.getValue();
var guiDataStore = this.getGuiDataStore();
guiDataStore.getProxy().url = 'gui_comp_items.php?id_metric=' + selected;
guiDataStore.load({
params: {
id_metric: selected
},
scope: this,
callback: function () {
var paramsRef = this.getParams();//this is the view where I'd like to create the combobox
var total = guiDataStore.getTotalCount();
if (total > 0) {
guiDataStore.each(function (model) {
if (model.get('type_guicomp') == 'combobox') {
paramsRef.down('fieldset[id=filterfieldset]').add(createComboBox(model.get('name_filter')));
paramsRef.down('fieldset[id=filterfieldset]').doLayout();
}
})
}
}
})
}
So my problem is, the first time I choose an item from the existing combobox and total = 0 , no combobox is created and everything is fine, then when I choose a value that returns total = 2, 2 new comboboxes are created, that's perfect. BUT, when right after that, I choose again a value with total = 0, the store is not updated and I STILL get 2 new comboboxes.
Is there a problem with my callback? Please any help would be much appreciated.

Answer 1

Once guiDataStore has 2 records in it, why would it be empty next time?
As in, do you empty the store between the various callback calls?