Howto specify a Model for List

Howto specify a Model for List

This is my JSON data returned from the server. I am not seeing my combo
getting loaded. What is wrong here?
{"suffixList":["-1","-2","-3"]}
Model:
Ext.define('ExtMVC.model.Suffix', {
extend: 'Ext.data.Model',
fields: [
{name: 'suffix'}
]
});
Store:
Ext.define('ExtMVC.store.Suffixes', {
extend: 'Ext.data.Store',
model: 'ExtMVC.model.Suffix',
autoLoad : false,
proxy: {
type: 'ajax',
url: 'http://'+window.location.host+'/populateCombo',
reader: {
type: 'json',
root: 'suffixList'
}
}
});
View:
{
xtype:'combo',
id: 'suffix',
name: 'suffix',
store : 'Suffixes',
displayField: 'suffix',
valueField: 'suffix'
}