smart rendering does not work with json

In dhtmlxgrid version 3.0 pro, I am unable to get smart rendering to work with json.

client side code:

mygrid = new dhtmlXGridObject('gridbox');
	mygrid.setImagePath("../../codebase/imgs/");
	mygrid.setHeader("Order,Index,Request info");
	mygrid.setInitWidths("50,275,*")
	mygrid.setColAlign("right,left,left")
	mygrid.setColTypes("ed,ed,ed");
	mygrid.setColSorting("na,na,na")
	mygrid.init();
	mygrid.setSkin("dhx_skyblue");
    mygrid.enableSmartRendering(true,50);
    mygrid.load("../common/testdata.json", "json");

My testdata.json looks like the below:

[code]{
total_count:1000,
pos:0,
rows:[
{ id:1001,
data:[
“100”,
“A Time to Kill”,
“John Grisham”,
“12.99”,
“1”,
“05/01/1998”] },

… etc …

{ id:10910,
data:[
“400”,
“Cousin Bette”,
“Honore de Balzac”,
“0”,
“1”,
“12/01/1991”] }
]
}[/code]

I realize this is a static file, but I would still expect the grid to render with 1000 rows.
Instead, it renders with just 50. The scroll bar does not go any further.

Please, make sure that the dhtmlxgrid_json.js extension is included on your page