Returns undefined value except in FF

[update 10-21-12] Sorry, my mistake... In FF, I am connected in admin mode, and in the other browsers in anonymous mode. And this data (vignette) is available only in admin mode.

---

I need some help about this issue:

1 - I have done a view with only one display page (style 'JSON data document' and path 'json-jc'). Data is an image path => see 'view_display' attached.

2 - The preview of this display seems to be OK, and 'json-jc' page is a valid JSON document => see 'view_preview' attached.

3 - The jQuery code is very simple:

$.ajax({
   	url: "http://localhost:8888/rkm/json-jc",
   	dataType: "json",
   	success: function(data) {
   		console.log(data);
   		$('li.jcarousel-item', context).css('width', '105px');
   		$('li.jcarousel-item-1', context).html(
   			'<img src="' + data.nodes['0']['node']['vignette'] + '">'
   		);
   	}
});

4 - It works fine in FF and the object returned is OK => see 'FF_console' attached.

5 - It doesn't work in Chrome, Safari and Opera, without throwing errors. The data 'vignette' returned is just undefined => see 'Chrome_console' attached.

Thanks in advance !