I need to populate my leavehistorygrid with this json but am not able to..what am i doing wrong????

My store is
Code:
Ext.define('AM.store.EMPLeaveRequest', {
extend: 'Ext.data.Store',
model: 'AM.model.EMPLeaveRequest',
autoLoad: true,
proxy: {
type: 'ajax',
url: 'data/employeeleave.json',
autoAppendParams: false,
reader: {
type: 'json'
}
}
});
My models are
Code:
Ext.define('AM.model.EMPLeaveRequest', {
extend: 'Ext.data.Model',
config: {
fields : [
{
name : 'ID',
type : 'int'
},
{
name : 'PlAvailedCount'
}
],
hasMany : [
{
model : 'AM.model.EMPLeaveHistory',
name : 'LeaveHistory',
associationKey : 'LeaveHistory'
}
]
}
});
Ext.define('AM.model.EMPLeaveHistory', {
extend : 'Ext.data.Model',
config : {
idProperty : 'ID',
fields: [{
name: 'Duration'
}, {
name: 'ApprovedBy'
}]
}
});
my json
Code:
[
{
"ID": 334,
"PLAvailedCount": "245234",
"LeaveHistory": [
{
"Duration": 43,
"ApprovedBy": "Shyam"
},
{
"Duration": 53,
"ApprovedBy": "Naveen"
}
]
}
]