print task not showing custom graphic layer as point clustering example

Faris_TawfiqAbdelFattah

dear all 

Am trying to print the custom graphic layer as the cluster point example ESRI JS clustering example using the print task class. the problem i had the is that when printing execute, the print results doesn't show the custom graphic layer (cluster) but showing only the base map layer (dynamic), am using arcgis 10.4 with 3.21 JS version, here is my code for the print functionality. is there something i should consider in my code.

function PrintMap() {
// print functionality
var printURL = "http://arcgissrv/server/rest/services/Utilities/PrintingTools/GPServer/Export Web Map Task"; (not the real url)
var printTask = new PrintTask(printURL);