Elasticsearch- Nested Aggregations D3 - angularjs

Question

I am trying to create D3 charts based on elasticsearch nested aggregation. While I can plot a chart based on the first aggregation, I am not sure why I cant plot a similar chart on the nested a subsequent aggregation. Can anyone suggest what I should do?
My code:
esClient.search({
index: 'vehicle',
body: {
query:{
match:{
_all:searchTerms
}
},
aggs: {
touchdowns: {
terms: {
field: "country",
size:5
},
aggs: {
corp: {
terms: {
field: "companyName",
size:5
}
}
},
}
},
sort: [sortObject],
from: resultsPage * 10,
}
}).then(function(es_return){
deferred.resolve(es_return);
//// Pie Chart first aggregation
var touchdowns = es_return.aggregations.touchdowns.buckets;
// d3 donut chart
var width = 600,
height = 300,
radius = Math.min(width, height) / 2;
var color = ['#ff7f0e', '#d62728', '#2ca02c', '#1f77b4'];
var arc = d3.svg.arc()
.outerRadius(radius - 60)
.innerRadius(120);
var pie = d3.layout.pie()
.sort(null)
.value(function (d) { return d.doc_count; });
var svg = d3.select("#donut-chart").append("svg")
.attr("width", width)
.attr("height", height)
.append("g")
.attr("transform", "translate(" + width/1.4 + "," + height/2 + ")");
var g = svg.selectAll(".arc")
.data(pie(touchdowns))
.enter()
.append("g")
.attr("class", "arc");
g.append("path")
.attr("d", arc)
.style("fill", function (d, i) { return color[i]; });
g.append("text")
.attr("transform", function (d) { return "translate(" + arc.centroid(d) + ")"; })
.attr("dy", ".35em")
.style("text-anchor", "middle")
.style("fill", "white")
.text(function (d) { return d.data.key; });
//// Pie Chart
var touchdowns = es_return.aggregations.touchdowns.buckets.corp.buckets;
// d3 donut chart
var width = 600,
height = 300,
radius = Math.min(width, height) / 2;
var color = ['#ff7f0e', '#d62728', '#2ca02c', '#1f77b4'];
var arc = d3.svg.arc()
.outerRadius(radius - 60)
.innerRadius(120);
var pie = d3.layout.pie()
.sort(null)
.value(function (d) { return d.doc_count; });
var svg = d3.select("#donut-chart").append("svg")
.attr("width", width)
.attr("height", height)
.append("g")
.attr("transform", "translate(" + width/1.4 + "," + height/2 + ")");
var g = svg.selectAll(".arc")
.data(pie(touchdowns))
.enter()
.append("g")
.attr("class", "arc");
g.append("path")
.attr("d", arc)
.style("fill", function (d, i) { return color[i]; });
g.append("text")
.attr("transform", function (d) { return "translate(" + arc.centroid(d) + ")"; })
.attr("dy", ".35em")
.style("text-anchor", "middle")
.style("fill", "white")
.text(function (d) { return d.assignee.key; });
}, function(error){
deferred.reject(error);
});
return deferred.promise;};