I am trying to build a single chart with both a line type series and a bubble type series on a numericY axis and a categoryDateTimeX axis.  The line series was drawn without any issues by itself.  As soon as I add the bubble series on the same chart, it didn't draw anything on the chart.  If I remove xMemberPath from the bubble series, the line series will show but no bubble series.  Any idea?  Thanks.

axes: [
{
name: "chartX",
type: "categoryDateTimeX",
},
{
name: "chartY",
type: "numericY"
}
],
series: [
{
name: "priceSeries",
type: "line",
title: "mid",
xAxis: "chartX",
yAxis: "chartY",
valueMemberPath: "price",
showTooltip: true
},
{
name: "qtySeries",
type: "bubble",
xAxis: "chartX",
yAxis: "chartY",
xMemberPath: "timestamp",
yMemberPath: "price",
radiusMemberPath: "qty",
unknownValuePlotting: "dontplot",
markerType: 'circle'
}
],