ExtJS: cannot call method 'getProxy'

ExtJS: cannot call method 'getProxy'

Why does this fail with cannot call method 'getProxy' of undefined?
{
name: 'customer_name',
xtype: 'combobox',
fieldLabel: 'Customer',
emptyText: 'ex. Google',
allowBlank: false,
queryMode: 'local',
store: Ext.create('Ext.data.ArrayStore', {
storeId: 'myStore',
fields: ['name'],
data: [ 'google', 'facebook', 'twitter']
}),
displayField: 'name'
}
taken from docs...
It 100% fails at this peice of code.