@elanchezhiyan,
In case of multi-series chart, you can loop through dataseries and pass dataseries index as well to position the image over the chart. Please find the code-snippet below.
function addMarkerImages(chart) {
for(var i = 0; i < chart.data.length; i++) {
customMarkers[i] = [];
for (var j = 0; j < chart.data[i].dataPoints.length; j++) {
customMarkers[i].push($("<img>").attr("src", chart.data[i].dataPoints[j].markerImageUrl)
.css("display", "none")
.css("height", 30)
.css("width", 30)
.appendTo($("#chartContainer>.canvasjs-chart-container"))
);
positionMarkerImage(customMarkers[i][j], i, j);
}
}
}
Also, check out this JSFiddle for complete working sample.

—-
Ranjitha R
Team CanvasJS