Drill down pie chart disappears - d3.js

Question

I make a drill down pie chart and it works well.
You can see it here.
But there is an issue:
1) click a node then it shows its children (level 1) or level 0 nodes.
2) Move mouse to another position and move back to the new node which contains its original position, the node disappears.
I think there is problem in this code (gradientPie.js)
var paths = gPie.selectAll("path").data(pieChart(currData), function(d) {return d.data.cat;});
var texts = gPie.selectAll("text").data(pieChart(currData), function(d) {return d.data.cat;});
var lines = gPie.selectAll("line").data(pieChart(currData), function(d) {return d.data.cat;});
var arcs = paths.enter().append("g").attr('class', 'slice');
arcs.append("path").attr("fill", function(d, i) { return "url(#gradient" + d.data.cat + ")"; })
.transition().duration(1000).attrTween("d", tweenIn).each("end", function(){
this._listenToEvents = true;
gradPie.transitioning = false;
})
.attr("id", function(d, i){return 'p' + i;})
.each(function(d) { this._current = d; });
arcs.append("text").attr("transform", function(d) {
var c = d3.svg.arc().outerRadius(radius * 1.4).innerRadius(radius).centroid(d);
return "translate(" + (0 + c[0]) + "," + (0 + c[1]) + ")";
})
.attr("dy", ".35em")
.attr("class", "text-main")
.style("text-anchor", "middle")
.style("fill", "#3f5763")
.style("font", "bold 14px Helvetica")
.text(function(d) {
$("#" + d.data.domID + " p").html(d.data.percent + "%");
return d.data.percent + "%";
});
arcs.append("line").attr("transform", function (d, i) {
var rAngle = ((d.startAngle + d.endAngle) / 2 - (Math.PI / 2)) * 180 / Math.PI;
return "rotate(" + rAngle + ")translate(" + radius * 1.1 + ")";
})
.attr("class", "line-ticks")
.attr('stroke-width', '1')
.attr("x2", -0.5 * radius)
.style("stroke", "#3f5763")
.style("fill", "none");
// Mouse interaction handling
paths.on("click", function(d, i){
if(this.childNodes[0]._listenToEvents && !gradPie.transitioning){
// Reset inmediatelly
d3.select(this).attr("transform", "translate(0,0)")
// Change level on click if no transition has started
paths.each(function(){
this.childNodes[0]._listenToEvents = false;
});
updateGraph(d.data.subfractions? d.data.cat : undefined);
}
})
.on("mouseover", function(d, i){
// Mouseover effect if no transition has started
if(this.childNodes[0]._listenToEvents && !gradPie.transitioning) {
// Calculate angle bisector
var ang = (d.endAngle + d.startAngle)/2;
// Transformate to SVG space
ang = (ang - (Math.PI / 2) ) * -1;
// Calculate a 10% radius displacement
var x = Math.cos(ang) * radius * 0.1;
var y = Math.sin(ang) * radius * -0.1;
d3.select(this).transition()
.duration(250).attr("transform", function() {
return "translate(" + x + ", " + y + ")";
})
}
})
.on("mouseout", function(d){
// Mouseout effect if no transition has started
if(this.childNodes[0]._listenToEvents && !gradPie.transitioning){
d3.select(this).transition()
.duration(150).attr("transform", function() {
return "translate(0,0)";
});
}
});
// Collapse sectors for the exit selection
paths.exit().transition()
.duration(1000)
.attrTween("d", tweenOut).remove();
texts.exit().transition()
.duration(100).remove();
lines.exit().transition()
.duration(100).remove();
Any help?