javascript - d3.js forceSimulation() with object entries -

have problem bubble chart.
used forcesimulation() array of objects , worked. changed data source , doesn't, if console displays no errors.
data object called "lightweight", following structure:
use append circles so:

// draw circles var node = bubblesvg.selectall("circle")    .data(d3.entries(lightweight))    .enter()    .append("circle")    .attr('r', function(d) { return scaleradius(d.value.length)})    .attr("fill", function(d) { return colorcircles(d.key)})    .attr('transform', 'translate(' + [w/2, 150] + ')'); 

then create simulation:

// simulate physics   var simulation = d3.forcesimulation()     .nodes(lightweight)     .force("charge", d3.forcecollide(function(d) { return d.r + 10; }))     .force("x", d3.forcex())     .force("y", d3.forcey())   .on("tick", ticked); // updates position of each circle (from function dom)    // call check position of each circle    function ticked(e) {       node.attr("cx", function(d) { return d.x; })           .attr("cy", function(d) { return d.y; });   } 

but circles remain on top of each other , not become bubble chart did before.
apologise if dumb question, new d3 , understood little of how forcesimulation() works.
example, if call multiple times different data, resulting simulation affect specified data?
in advance!