Created Issue: Method add_populated on ajax CascadingDropDown is undefined (ajaxControlToolkit 7.0123) [27354]

Method add_populated is not working on Cascasing Drop Down, and display error message undefined after upgrade ajax Control Toolkit to version 7.0123.

Previous version is still working (ajax control Toolkit version 4.1.51116.0)

The script is below

function pageLoad(sender, args) {
$find("BehavArea").add_populated(onPopulatedArea);
$find("BehavBranch").add_populated(onPopulatedBranch);
}

function onPopulatedArea() {
if (GetValueTxtByClientID("<%=hidIsUserBranch.ClientID%>") == "1") {
$get("<%=ddlAreaSearch.ClientID%>").disabled = true;
}
}

function onPopulatedBranch() {
if (GetValueTxtByClientID("<%=hidIsUserBranch.ClientID%>") == "1") {
$get("<%=ddlBranchSearch.ClientID%>").disabled = true;
}
}

regards