Can't make working the 'root' property of Ext.util.Sorter to sort a store

Hi,

I am trying to sort my store depending on the following hierarchy "data.lastItem.creation" with data described as follow:

"1: constructor

data: Object1

[...]

lastItem:

creation: 1417530818510

[...]"

My sorter is defined as follow:

Code:

store: menuCheckItem.getStore(),
root: menuCheckItem.root, ('data', 'lastItem' or 'data.lastItem')
property: menuCheckItem.property,

I've tried to set the root property to 'lastItem' or event 'data.lastItem', nevertheless I still get the following error:

"

Uncaught TypeError: Cannot read property 'creation' of undefined

Ext.define.defaultSorterFn

"

I don't understand why it can't reach the lastItem structure.

Thank you very much.

Kind Regards,

Michael Jeulin-L.

Can't make working the 'root' property of Ext.util.Sorter to sort a store