I’ve tried setting this up with the example as well as my custom code below. When I load my page, the code fires with no errors, but the table comes out blank (headers only) see:
cl.ly/3m3p0K0l0w3r293G2J0d
My code:
    <link rel="STYLESHEET" type="text/css" href="dhtmlx/dhtmlxGrid/codebase/dhtmlxgrid.css">
    <script src="dhtmlx/dhtmlxGrid/codebase/dhtmlxcommon.js"></script>
    <script src="dhtmlx/dhtmlxGrid/codebase/dhtmlxgrid.js"></script>
    <script src="dhtmlx/dhtmlxGrid/codebase/dhtmlxgridcell.js"></script>
    <script src="dhtmlx/dhtmlxGrid/codebase/ext/dhtmlxgrid_json.js"></script>
	<script  src="dhtmlx/dhtmlxTreeGrid/codebase/dhtmlxtreegrid.js"></script>
    <div style="width: 600px">
        <div id="pagegrid"></div>
    </div>
window.onload = function()
{
    var pagegrid;
    pagegrid = new dhtmlXGridObject('pagegrid');
    pagegrid.setImagePath(STATIC_PATH+"dhtmlx/dhtmlxGrid/codebase/imgs/");
    pagegrid.setHeader("Tree, ID, Title, Parent, Body Content");
    pagegrid.setInitWidths("60,60,*,*,*");
	pagegrid.setColTypes("tree,ch,ch,ch,txt");
    pagegrid.setSkin("light");
    pagegrid.init();
    pagegrid.load('/cms/data/page/tree/', 'json');
}
My JSON:
dpaste.com/hold/648376/
I’ve also checked the table (via firebug) to make sure that nothings hiding in an overflow or whatever. I’m on a trial of the software at the moment, but that shouldn’t matter.