Selection changed in drop down using jquery

Dear All,


Am trying to display tree view structure based on the dropdown selection using JQUERY IN ASP.NET
i have done the tree view, if i select any dropdown value then its working fine
but i cannot display tree, if i select second value from dropdown

Note: i cannot display second option from dropdown 
      i alwways displaying only one selection

// ======================================== //
		// ===> Selection Changed in Drop Down <=== //
		// ======================================== //
		
		$(function () 

						{
						try
						{
						 $("#cmbGroupName").on('click', function (e) 
						 {
						 LogInUser = document.getElementById("hdnuser").value;
						 var cmbGroupName=document.getElementById("cmbGroupName").options[document.getElementById("cmbGroupName").value].text;
						 var strxml2='SelectionChangeApp';
						 if(document.getElementById("cmbGroupName").options[document.getElementById("cmbGroupName").value].text != "Select GroupName")
						 {
						
                           $('#divAppMenus0').jstree({'plugins':["defaults","json_data","checkbox"],
                           'core' : {
                            data : {
                            type: "POST",
                            url : '../masterutil/GetMasterGroup_TEST.aspx?User=' + document.getElementById("cmbGroupName").options[document.getElementById("cmbGroupName").value].text + "&t=" + t + "&LogInUser="+ LogInUser + "&ReqMode="+ ReqMode+ "&strxml2="+ strxml2 + "&cmbGroupName="+ cmbGroupName,
                            contentType: "application/json; charset=utf-8",
                            dataType : "json"
                            
                                  
                                   }
                            });
                         }
                      
                         }
                      
                            
                         });
                         }
                         catch(e)
                         {
                              ShowScriptError(e,"cmbGroupName");
                         }
                         });