Add Named Model to XML ComboBox

Hi experts

I have a sap.m. App with an XML-View and some Comboboxes. I need to use named Models. I was able to implement a Combobox with non named model, but when I use named models, I can Display the Combobox and open it. I'm also able to see the correct NUMBER of dataset entries in the Dropdown but there are no Texts.

I implemented the following coding:

in Controller.js

var oModel = new sap.ui.model.json.JSONModel();

oModel.loadData("model/area.json", "", false);

this.getView().setModel(oModel, "area");

in view.xml

<...xmlns:core="sap.ui.core... >

<ComboBox items="{ path:'area>/data', sorter: { path: 'area>/Name' } }">

<core:Item key="{Id}" text="{Name}"/>

</ComboBox>

Any Solutions for my Problem?

Thanks and regards,

Sebastian